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HOW TO BUILD 



EMBRACING THEORY DESIGNING AND THE CONSTRUCTION 
OF DYNAMOS AND MOTORS. 

y 

By Edward Trevert. 

t /• 


With Appendices on Field Magnet and Armature 
Winding. Management of Dynamos and 
Motors, and LTseful Tables 
of Wire Gauges. 


ILLUSTRATED. 

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LYNN, MASS. : 


Bubier Publishing Company. 


1902. 



































THE LIBRARY OF 
CONGRESS. 

One Copy Received 


APR. 22 *902 


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Copyrighted 1894, 

By BUBTER PUBLISHING CO., 
Lynn, Mass. 

Copyrighted 1902, 

By BUBIER PUBLISHING CO., 
Lynn, Mass. 



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PREFACE. 


Almost the first piece ot electrical apparatus the student wishes 
to construct is the dynamo, in fact it is important that he should 
be familiar with this machine at the beginning of his studies in 
electricity. It is the purpose of this book to give practical 
directions for building smal"Pcfyhamos* and motors, and these direc¬ 
tions are accompanied with working drawings which will enable 
the reader to understand the text more clearly. The machines 
described have been carefully selected both for efficiency and beauty 
of form. They are easy to build, the design of castings being for 
as few pieces as possible. 

This book is intended as a practical treatise, and in no way 
is it to be considered as technical. Some theory, however, is 
given to help the reader in a general way. The chapters on 
commercial dynamos and motors are added to show the general 
construction of large machines. The chapter on management, and 
the one containing useful tables, the author hopes will add to the 
value of the book. No foreign dynamos or motors have been 
described, owing to the fact that there is sufficient material for 
description in American machines to answer every purpose of this 
work. 


Lynn, Mass., June 30, 1S94. 


EDWARD TREVERT. 









PREFACE TO SECOND EDITION. 


Eight years having passed away since this book was first published, 
the publishers have requested me to make some additions and bring 
it up to date. This I have done, and trust that my effort will prove 
satisfactory to the reader. 

EDWARD TREVERT. 

Lynn, Mass., 1902. 


CONTENTS. 

CHAPTER PAGE 

I. Historical Notes. 7 

II. Principles of Dynamo Machines . n 

III. Methods of Field Magnet Winding.22 

IV. Forms of Field Magnets.27 

V. Armatures. -5 

VI. How to Make a Toy Electric Motor . 4 j 

VII. How to Make a Small Dynamo .49 

VIII. How to Build a One-fourth H.P. Motor or Dynamo ... 65 

IX. How to Build a Two-Light Dynamo.97 

X. How to Build a One-half H.P. Dynamo or Motor . . . . 113 

XI. How to Build a One-Horse Power Motor or Dynamo . . . 143 

XII. How to Build a Twenty-Light Dynamo.177 

XIII. How to Build a iooo-Watt Alternating Current Dynamo 

or Motor.191 

XIV. Types of Commercial Dynamos. (Direct Current) . . . . 217 

XV. Types of Commercial Dynamos. (Alternating Current) . . 251 

XVI. Types of Commercial Stationary Motors.268 

XVII. Types of Commercial Railway Motors.289 

APPENDIX 

A. Management of Dynamos and Motors.308 

B. Useful Tables.312 

C. Some Practical Directions for Armature Winding .... 320 

D. Field Magnet Winding (Field Formula).328 

Index ........ 331 























HOW TO BUILD 




Dyr}air|o-Electric Mact|ir|ery, 

CHAPTER I. 

HISTORICAL NOTES. 


F ARADAY, in 1S31, made the discovery of what is termed 
Magneto-Electric Induction of Currents. He showed that 
induced currents of electricity could be produced in a closed 
coil of wire, by means of currents started or stopped in a 
neighboring coil. He also induced electric currents in a coil 
moved in front of the poles of a powerful steel magnet. These 
experiments showed the first principles of all dynamo-electric 
machinery. About this time he also constructed his first mag¬ 

neto-electric machine. u *It consisted of a disc of copper 12 
inches in diameter and about one-fifth of an inch in thickness, 
fixed upon a brass axle. It was mounted in frames so as to 

allow of revolution, its edge being at the same time introduced 
between the poles of a large compound permanent magnet, the 
poles being about half an inch apart.” The edge of the 

plate was well amalgamated, for the purpose of obtaining a 
good but movable contact, and a part around the axle was also 
prepared in a similar manner. Conducting strips of copper and 
lead to serve as electric collectors, were prepared so as to be 
placed in contact with the edge of the copper disc; one of 
these was held by hand to touch the edge of the disc between 


* Thompson’s “Dynamo-Electric Machinery.” 


t Faraday’s Experimental Researches. 






3 


DYNAMO-ELECTRIC MACHINERY. 


the magnet poles. The wires from a galvanometer were con¬ 
nected ; the one to the collecting-strip, the other to the brass 
axle; then on revolving the disc, a deflection of the galvano¬ 
meter was obtained, which was reversed in direction when the 
direction of the rotation was reversed. “Here, therefore, was 
demonstrated the production of a permanent current of electricity 
by ordinary magnets.” 

All the early dynamos were made with permanent field 
magnets, the armature being soft iron cores with spools of wire 
placed over them. These machines gave an alternating current. 

*In 1S41 “Wheatstone produced the first continuous current 
machine. This machine had five armatures, each consisting of a 
pair of short parallel cylindrical coils with iron cores, and each 
having a simple split tube commutator. These armatures were 
arranged in a row along a single shaft with six compound 
steel magnets between them. The five armatures being so set 
that they came successively into the position of the greatest 
activity, no two of them being commuted at the same instant. 
They were connected in series with one another by wires, which 
joined the positive brush—a brass spring—of one to the nega¬ 
tive brush of the next.” 

Four years later, 1845, Wheatstone and Cooke patented the use of 
electro-magnets instead of permanent steel magnets in such machines. 

In 1848, Jacob Brett made the important suggestion of 
causing the current developed in the armature by the permanent 
magnetism of the field magnets to be transmitted through a coil 
of wire surrounding the magnet, so as to increase its action. 
This appears to be the first suggestion of the principle of the 

i 

self-exciting dynamo. 

o J 


♦Thompson’s “Dynamo Electric Machinery.” 



HISTORICAL NOTES. 


9 


In 1S56, C. W. S iemens provisionally patented the shuttle- 
wound longitudinal armature, invented by Werner Siemens. 

In 1S66 and 1S67 Wilde produced alternating current ma¬ 
chines. The latest had a number of bobbins mounted on the 
periphery of a disc rotating between two opposite crowns of 
alternately polarized field magnets. This type survives to the 
present day. 

In 1S64, Pacinotti devised a machine with a ring armature, 
the core consisting of a toothed iron wheel between the teeth of 
which the coils were wound in sixteen separate sections. 

In 1S70, Gramme invented a ring armature without 
teeth; the principle of which was winding a continuous coil in 
separate symmetrical sections around a ring, or other figure of 
revolution, until it was entirely overwound with wire. By wind¬ 
ing an armature with a number of such symmetrically grouped 
coils, which pass successively through the magnetic field, currents 
can be obtained that are practically steady. In 18S0, Elihu 
Thomson and E. J. Houston invented a unique dynamo, hav¬ 
ing cup-shaped field-magnets and a spherical armature wound 
with three coils. Since 1SS3, large multipolar dynamos have 
been invented by Siemens, Halske, and others. Large alternat¬ 
ing current machines have also been placed upon the market by the 
Westinghouse Company, General Electric Company, and others. 

The first electric motor in the true sense of the word may be 
said to be Barlow’s rotating wheel. This he produced in 1S23. 
Barlow discovered that by passing an electric current from the 
centre to the circumference of a copper disc placed between the 
poles of a powerful magnet, the disc would revolve. The cur¬ 
rent was sent perpendicularly through the disc from its axis to 
its circumference, when it passed into a cup of mercury. 

u 






IO 


DYNAMO-ELECTRIC MACHINERY. 


was simply the reverse of Faraday’s experiment. Various motors 
of more or less importance were invented after this date by 
Abbe Salvatore, Dal Negro, Jacobi, Froment, Du Moncel and 
others. In 1837 Thomas Davenport, a blacksmith of Brandon, 
Vt., patented the first electric motor ever invented in the United 
States. Among other early inventors of this country were Page and 
Vergnes. The reversibility of the dynamo is claimed to have been 
discovered by Siemens in 1S67. It was put into practical appli¬ 
cation in 1873 at the Vienna Exposition by Hippolite, Fontaine, 
and Bregnet. In this case a Gramme dynamo machine was used 
as a motor, the current being supplied by a similar machine, 
the machine being driven by a gas engine. Improvements have 
been steadily going on up to the present time, and we now have 
the inventions of Edison, Thomson, Sprague, Tesla and others. 


11 


CHAPTER II 


PRINCIPLES OF DYNAMO-MACHINES 


DYNAMO is a machine for generating electricity by mechan- 



x \ ical means. All dynamos are capable of serving two dis¬ 
tinct functions. They may be used to generate electricity by me¬ 
chanical force, as when the machine is driven by a steam en¬ 
gine or a water wheel, or they may be run as motors and develop 
mechanical power, as when supplied by an electric current from 
another dynamo or a voltaic battery. 

All dynamo-machines have a field magnet and an armature. 
The function of the field magnet is to furnish a magnetic field 
in which the armature revolves. 

The function of the armature is to revolve within the mag¬ 
netic field, thereby cutting the lines of force while carrying the 
electric currents in its coils or conductors. 

♦ “It must be remembered that there is a two-fold action be¬ 
tween a conducting wire (forming part of a circuit) and a mag¬ 
netic field : Firstly , if the conducting wire is forcibly moved 
across the magnetic field (so as to cut the magnetic lines), elec¬ 
tric currents are generated in the conductor, and a mechanical 
effort is required to move the conductor. This action, discovered 
by Faraday, is termed ‘magneto-electric induction.’ In every case 
the induction or generation of currents necessitates the applica- 

* S. P. Thompson, “Dynamo-Electric Machinery.” 









DYNAMO-ELECTRIC MACHINERY. 


I S 


tion of mechanical power and the expenditure of energy. This 
is the principle of the dynamo used as a generator. Secondly , 
if the conducting wire, while situated in the magnetic field, is 
actually conveying an electric current (from whatever source) it 
experiences a lateral thrust, tending to move it forcibly, parallel 
to itself, across the magnetic lines, and so enables it to exert 
power, and to do work. This action, which is the converse of 
the former, is the principle of the dynamo when used as a mo¬ 
tor. In the first case, power is required to drive the armature; 
in the second, the armature rotating becomes a source of pow¬ 
er. If we have the magnetic field, and supply power to drive 
the rotating conductor, we get the electric currents; if we have 
the magnetic field and supply the electric currents to the con¬ 

ductor, it rotates and furnishes power. Whether the machine be 
used as a generator or a motor, the magnetic field must be pres¬ 
ent : hence the most important theory is the theory of the mag¬ 
netic field.” As theoretically, every dynamo may be worked either 
as a generator or a motor, the reader should be able to 
frame a general theory for any machine serving either of the 
two converse functions. All dynamos are based on the princi¬ 
ple of Faraday’s discovery,—that electric currents are generated 
in conductors by moving them in a magnetic field, and with 

dynamos this field is produced by field magnets. All magnets 

are surrounded by what is known as the field of force. The 

familiar experiments with the magnet and iron filings give 
US' some idea of the character of this field, for the filings always 
adjust themselves along certain lines, generally curves, depending 
for their shape upon the form of the magnet. If a bar magnet 
is used in this experiment the iron filings will be found to have 
arranged themselves into lines as shown in Figure i. 


PRINCIPLES OF DYNAMO AIACHINES. 


*3 



FIGURE I. 


If the experiment is made by dusting the iron filings into 
the field of one end or pole of a bar magnet the lines will 
be found as shown in Figure 2. 



Thus we see that the region surrounding the magnet is 
conceived as being penetrated by “lines ot force,’ which radi- 







H 


DYNAMO-ELECTRIC MACHINERY. 


ate from the poles and are parallel to the lines of iron filings. 
They emerge from the magnet something like the bristles of a 
brush and always form closed curves, that is, they always return 
by longer or shorter routes to the body of the magnet and 
through it to the starting point. It is for this reason that it is 
impossible to make an unipolar magnet. Every magnet must 
have two poles, a north and south. These lines do not pass 
with equal facility through all substances. Most bodies offer a 
high resistance to them, but iron, steel and nickel, are good mag¬ 
netic conductors. Magnetism always follows the path of least 
resistance, and with a given magnetizing force ; the intensity of the 
resulting magnetism is enormously increased by the presence of 
iron. It is for this reason that iron is used in the field mag¬ 

nets of dynamos and motors, and it is of the greatest impor¬ 
tance that the magnetic circuit or path over which the magnetic 
force passes shall have a large cross section and a low 
resistance. 

Whenever a conductor of electricity is passed through the 

field of force surrounding a magnet, at right angles to the 
lines, an electro-motive force is set up in it, depending upon 

the length of the conductor, the speed at which it moves, and 
the intensity of the field. This fact is the one utilized in the 

construction of dynamos and forms the basis of our calculations, 
for, knowing the strength of the field magnets, the length of 
wire on the armature, and the speed at which it revolves, we 

have all the data necessary to calculate our electromotive force. 

The simplest form of armature is the shuttle armature, 
devised by Siemens. It consists of a single coil of wire wound 
lengthwise upon an iron “shuttle”, see Figures 3 and 4. 

When this is revolved between the poles of a magnet a current 


PRINCIPLES OP DYNAMO MACHINES. 


J 5 




is set up in the wire, the direction of which may be determined 
by the following “rule of thumb.” Spread out the thumb and 
first two fingers of the right hand in such a way that each will 
be at right angles to the other. See Figure s;. 



Then if the thumb be pointed in the direction of motion 
of the wire, and the forefinger in the direction of the lines of 
force (that is from the north to the south pole of the magnet), 
the middle finger will be pointing in the direction of the 
induced current. It will be seen by applying the rule to the 
coil just spoken of, we find that the current in the wire will 
reverse at each half revolution, and that if we desire the cur- 








DYNAMO-ELECTRIC MACHINERY 


16 

rent in the external circuit to be in one direction, we must 
place what is known as a commutator at the " point where the 
current is led from the armature. The commutator in this case 
will consist of two halves of a metallic cylinder attached to the 
armature shaft, but insulated from it and each other. The ends 
of the coil are fastened one to each half of the cylinder, and 
the brushes or collectors which lead off the current rub against 
them. See Figure 6. 



figure 6 . 

When the armature is in the position as shewn in Figure 
6 , the current in the external circuit will flow as indicated by 
the arrow, and when the armature makes half a revolution its 
current will be reversed, but at the same time its connection 
Vvith the external circuit is reversed by the commutator, and the 
current still flows there in the same direction. When the arm¬ 
ature has made a quarter revolution, or stands at right angles 
to its present position, the brushes will touch both segments of 






























PRINCIPLES OF DYNAMO MACHINES. I 7 

the commutator, and the coil is short circuited, but at the same 
time it will be seen that the wires of the coil are not moving 
across the lines of force but parallel to them, and that they are 
therefore generating no electro-motive force, so that there is no 
harm • done; that is, there would be none if the above statement 
were accurately true. Practically, if the coil has any breadth it 
cannot be moving parallel ’to the lines of force at every point, 
at the same instant, and a sufficient current may be generated 
during this period to cause a spark to form when the short cir¬ 
cuit caused by the brushes passing from one segment of the 
commutator to the next, is broken. In well-designed machines, 
this can be avoided by attention to the shape of the pole pieces 
of the fields; that is, by so making them that few, if any, 
lines of force are cut by the coils when short circuited. The 
current given by the above arrangement, while it flows in but 
one direction, is, nevertheless an intermittent one, varying from 
its maximum when the coil is horizontal, to nothing when it 
is vertical and short circuited. If we wind another coil on the 
armature with its plane at right angles to the first, we shall 
evidently lessen this tendency, for when one coil is in its idle 
position, the other will be doing its best work, and vice versa , 
but there will still be a jog in the current strength, though to 
i much smaller degree. 

Three coils would evidently be a step further in the right 
direction, and in fact, the greater number of coils we use, and a like 
number of commutator segments, the nearer we come to having 
a smooth current. The number is limited by the difficulty of con¬ 
struction, which increases with each additional commutator seg¬ 
ment. In the usual construction of the closed coil armatures the 
end of one coil is connected to the beginning of its next neigh- 


2 






iS 


DYNAMO-ELECTRIC MACHINERY. 


bor, and a wire is taken from this junction to a commutator 
bar and there must be as many commutator segments as coils. 
This arrangement is best shown on a Gramme ring, but the prin¬ 
ciple is the same for any style of armature. See Figure 7. 


jv 





FIGURE 7. 

In the sketch showing this arrangement it may be seen that 
the current in the armature is flowing in the opposite direction, 
in the halves made by the line A B. In each case it flows 
from B to A, and therefore if the brushes be placed on the 
line of A B, they will be in proper position to take the cur¬ 
rent. In an open coil armature, that is, one in which each 
coil is by itself, and has no connection with the others, the 
brushes must be on a line at right angles to A B, or so that 
they will take off the current when the coil is generating the 
highest electromotive force. The flow of electricity (that is, in 
steady currents) in a conductor is, by ohms law, directly pro¬ 
portional to the electromotive force, and inversely proportional 
to the resistance of the conductor. Sylvanus P. Thompson says 












PRINCIPLES OF DYNAMO MACHINES. 


l 9 


“For sudden currents, or currents whose strength is varying 
rapidly, this is no longer true. And it is one of the most im¬ 
portant matters, though one too often overlooked in the con¬ 

struction of dynamo-electric machinery, that the ‘ resistance ’ of a 
coil of wire, or of a circuit, is by no means the only obstacle 
offered to the generation of a momentary current in that coil 
or circuit; but that, on the contrary, the 1 self-induction ’ ex¬ 
ercised by one part of the coil or circuit on another part or 

parts of the same, is a consideration, in many cases, quite as 
important as, and in some cases more important, than the re¬ 
sistance.” The method of field winding will depend largely 

upon the form of the field core, and we will briefly discuss 
this before going further. 



Cast-iron cores will, in most cases, be cheapest to construct, 
but a wrought core is always the most effective electrically. A 
cast-iron core can be made almost any shape, but there is a 

limit to the number of shapes into which wrought-iron can be 
made, unless an expensive amount of forging is done. One 

wrought-iron form, which can be made without much trouble, 
is shown in Figure S. 

After bending into shape, the space for the armature can 
be bored out, and the winding slipped over spools. The fields 

of a dvnamo must be connected up in such a way as to make 










20 


DYNAMO-ELECTRIC MACHINERY. 


the pole pieces north and south magnetic poles. To know if 

the pole is north or south, look at the winding at the end 

from which it projects, and if the current goes in the direction 
of the hands of a watch, the pole is south, and if in the con¬ 

trary direction, it is north. See Figure 9. 



If more than two poles are used, they must alternate north 
and south. In making the armature and field connection you 
must be careful to get the machine connected for the way in 
which it is to run. A dynamo or motor will not run in either 
direction indifferently; if you run the dynamo in the wrong 
direction it will not generate a current. 

* “ The name of ‘field-magnet’ is properly given to that 
part which, whether stationary or revolving, maintains its mag¬ 
netism steady during the revolution; and the name armature is 
properly given to that part, whether revolving or fixed, which has 
its magnetism changed in a regularly repeated fashion, when the 
machine is in motion.” 

In this book, however, we shall treat only of dynamos in 
which the armatures revolve, the field magnet remaining sta¬ 
tionary. 

Electro-magnets are practically magnetic only when a current 
of electricity is passing through their coils. There, however, 
remains a feeble residual magnetism in the pole pieces of 


* S. P. Thompson’s “Dynamo-Electric Machinery.’’ 



PRINCIPLES OF DYNAMO MACHINES. 


2 I 


dynamos, which, when excited by rotating the armature at a 
high rate of speed, within the magnetic field, will induce a 
small current in the coils, which rapidly increases, and on being 
transmitted through the coils of the electro-magnets, augments 
their magnetism and produces in them still stronger currents. 






22 


DYNAMO-ELECTRIC MACHINERY. 


CHAPTER III. 

METHODS OF FIELD-MAGNET WINDING. 

T HERE are two types of dynamos — the continuous current 
and the alternating current. In the continuous current 
machine the current generated is made to flow in one direction 
by the use of a commutator, from which the current is col¬ 
lected by brushes and carried to the external circuit. In the 
alternating current machine the current generated flows at rapid 
intervals, first in one and then in the opposite direction. This 
dynamo, having no commutator, a collector of two metal rings 
is necessary, on which the brushes rest. The field-magnet of 
this machine must have a continuous current to excite it, and 
this current is usually supplied by another small continuous cur¬ 
rent machine, which is called the exciter. There are five simple 
methods of exciting the magnetism that is to be utilized in the 
magnetic field. 

In the “magneto machine ” (found only in small types 
today) no attempt is made to make the machine excite its own 
magnetism, this being provided for by the use of a permanent 
magnet of steel. It has the disadvantage of the permanent 
magnets becoming gradually diminished in strength by every 
mechanical shock or vibration to which the machine is subjected. 
A diagram of this machine is shown in Figure io. 


FIELD-MAGNET WINDING. 


It is used principally for magneto call bells and for medical 
and experimental purposes. 



The separately excited dynamo (a diagram of which is 
shown in Figure 11) possesses the property that, saving for 



reactions due to the armature current, the magnetism in its 
field, and the electro-motive force of the machine, is independent 
of changes of resistance going on in the working circuit. This 
machine may be governed by altering the speed, or by alter¬ 
ing the amount of magnetism that passes across the armature. 
There are two other ways of weakening the effective magnet¬ 
ism, both by reducing the exciting current: (i) by introducing 








































2 4 


dynamo-electric machinery. 


a resistance into the exciting circuit; (2) by altering the 
number of turns of wire around the field magnets. 

There are three kinds of windings for self-exciting dynamos, 
namely: the series, the shunt, and the compound. 

The series dynamo has but one circuit. The current geneiated 
is passed through the field-magnet coils, which are connected in 
series with the armature and external circuit. See Figure 12 



FIGURE 12. 


This machine will not generate a current until a certain 
speed has been obtained, or unless the resistance of the circuit 
is below a certain limit; the machine refusing to magnetize its 
own magnets when there is too much resistance or too little 
speed. This type of machine is liable to reverse its polarity, a 











FIELD-MAGNET WINDING. 


25 


serious fault, which unfits it for use in electroplating and for 
charging storage batteries. These machines are generally em¬ 
ployed for arc lighting. 

In the shunt wound dynamo the field-magnets are wound 
with many turns of fine wire, to receive only a small portion 
of the whole current generated in the armature. These coils are 
connected to the brushes of the machine and constitute a by-pass 
circuit, or what- is called a shunt. See Figure 13. 



' In the compound wound dynamo we have a combination of 
the series and shunt winding. The field-magnets aie wound 
with two sizes of wire — coarse wire, which is in series with 
the armature and the external circuit, and a finei wiie, which 
is in shunt with the brushes. This machine is nearly self-reg¬ 
ulating, and is used largely for incandescent lighting. If the 
shunt coils be comparatively few, and of high resistance, theieby 
causing their magnetizing power to be small, the machine will 
give approximately a uniform pressure of a few volts; whereas, 
if the shunt be relatively a powerful magnetizer, as compared 
with the few coils of the main circuit, it will be capable of 













































2 6 


DYNAMO-ELECTRIC MACHINERY. 


giving a constant pressure of a large number of volts. Each 
coil corresponds to a certain rate of speed, depending on the 
arrangements of the machine. A diagram of the compound 
wound dynamo is given in Figure 14. 



FIGURE 14. 








































FORMS OF FIELD MAGNETS. 



% 

CHAPTER IV. 


FORMS OF FIELD MAGNETS. 


Most dynamos have but one field magnet, but special 
forms are made in which several magnetic “fields” or regions 
are available. Electro-magnets, more powerful and compact 
than permanent forms, are almost exclusively adopted. The 
ends of “field magnets” are usually made to embrace a large 
portion of the revolving armature. Where a permanent mag¬ 
net is used as in a magneto-machine the magnet can be with 
extensions, as shown in Figure 15. These ends are called pole- 







< 


) s 


figure 16 . 


pieces as they become the poles of the magnet. Five separ¬ 
ate pieces are usually joined together to form an electro-magnet 
for the type of dynamo shown in Figure 16. The two pole- 
pieces are of cast iron, the two cylindrical “cores” of wrought, 
as is also the “magnet yoke” which connects the cores together. 

























28 


DYNAMO-ELECTRIC MACHINERY. 


The surfaces where these separate pieces touch are made very 
smooth and flat, in order that the magnetic circuit may be 
as if in only one piece of metal. This form is convenient 
for handling and allows easy application of the coils of wire. 
It is not best to wind this directly on the iron, but to have it 
wound on detachable spools. Simple brass rings connected 

with a sheet-iron or tin cylinder is strong enough, and the 
spools fit loosely over the cores. Such arrangements as shown 
in Figures 15 and 16 furnish magnets with “salient” poles, 
that is, virtual j^oles at the very ends of the cores. If another 
set of cores be added to the other side of the pole-pieces a 
magnetic field of twice the strength of the above arrangement 
can be obtained. See Figure 17. 




FIGURE 17. 

In this form the poles are “consequent,” for the magnetism is 
available in pole-pieces which are interruptions in the otherwise 
continuous iron. Figures 18 and 19 show a type of field 
magnet where only one core is used, consequently only one 
snool of wire is necessary. Figure 18 shows one position 




















FORMS OF FIELD MAGNETS 


2 9 



and Figure 19 the same with its 
doubling this form we have Figure 


| N 




s 


figure 19. 

core perpendicular. 
20. By lengthenin 


O' 

& 


By 

the 


■N 





JWL 


S 


FIGURE 20. 

pole-pieces into cores this form becomes merged into Fig¬ 
ures 21 and 22. 

Just which four of these fiekl-magnets is best to use depends 



figure 21 . 

























































DYNAMO-ELECTRIC MACHINERY. 


3 ° 

on the purpose for which the dynamo or motor is designed. 
Sometimes, for the same purpose, different forms work equally 
well. Usually dynamos for continuous currents have but two 
poles as shown in these figures. By increasing the number 



FIGURE 22 . 

of poles, as shown in these figures, the armature will receive 
the desired number of inductions at a slower speed of rotation. 
A four pole field-magnet is shown in Figure 23 1 The cores 
are also used as pole-pieces. Figure 24 shows a six pole 
field-magnet. This form can be used for continuous current 
but it is better adapted for alternating. An alternating current 




FIGURE 23. FIGURE 24. 

dynamo should have a large number of poles in order to give 
a rapid alternation. Two hundred and fifty reversals per 
second is commonly attained. It is not unusual for an alter- * 
mating machine to have from sixteen to twenty poles. For 
future machines the promise is for even a larger number. The 


























FORMS OF FIELD MAGNETS. 


3 1 


more poles a machine has the slower the speed can be, and 
the tendency now is toward slow running machines. For arc 
dynamos the amount of iron in the magnets should be compara¬ 
tively small, but a large amount of copper wire needs to be 
used on the spools. Arc dynamos are series-wound, so that the 
entire current from the armature circulates around the field-cores. 
The field is in “series” with the rest of the circuit. When 
this winding is used the field-magnet experiences every fluctua¬ 
tion of the current which lights the lamps, which varies the 
magnetism and is utilized in adjusting the regulator. An arc 
dynamo preserves a current of uniform strength, but the poten¬ 
tial or voltage varies according to the number of lamps supplied 
in the circuit. 

A dynamo for incandescent lighting or for supplying power 
to motors should have a constant voltage, but the strength or 
quantity of current should be dependent on the demand. For 
such a machine there should be a very massive field-magnet. 
The winding should be in “ shunt,” that is, the field spools 
should be in a circuit independent of the working circuit. This 
subtracts a certain amount from the useful output of the 
machine, but if the wire is fine and of considerable length, the 
resistance being sufficient to allow only about one-hundredth 
part of the whole current to pass around the field-magnets, the 
magnetism is thus kept nearly constant, and the potential is 
uniform. 

Absolute constant potential can be obtained by “compound” 
winding. To get just the right amount of wire on the field- 
magnet is no easy task, without elaborate data. Manufacturers 
usually wind a temporary coil on each spool for experimental 
purposes. These spools are placed ovei the “coies. The 


are 






DYNAMO-ELECTRIC MACHINERY 


3 3 

armature is then rotated at its calculated speed, and current 
from another source is sent through the temporary field-wire. 
From measurements of the number of turns of wire, and the 
current necessary to bring the machine to its proper output, the 
final winding may be calculated. It is desirable to use as large 
wire as possible, in order that the heating effects be low. 
About 1000 amperes to the square inch of cross-section of wire 
is a safe allowance. For arc dynamos the wire needs to carry 
about io amperes. For a “shunt” wound dynamo from one 
to three amperes. In a compound wound dynamo the shunt is 
the same as in the previous case, but the series coils needs to 
be sufficiently large to carry, in some cases, several hundred 
amperes. 

A dynamo should be designed in such a manner as to 
economize material. The iron of th,? magnet should also be 
compelled to form the frame for the matnine, and give places 
for the armature bearings. No part of the magnetic circuit 
should have less cross section of iron than the “ cores.” This 
rule has not always been observed, hence a large amount of 
external magnetism, or leakage, has been the result. That is to 
say, that some of the magnetic lines which are excited in the 
field-magnet fail to pass through the armature, and leak out 
sideways, thereby constituting a “stray field” around the dyna¬ 
mo. In some machines more than one-half of the magnetic 
lines are wasted in this way. The nature of this leakage may 
be easily comprehended by remembering that air is a magnetic 
conductor, though not as good a conductor as iron. A perfect 
dynamo will exhibit no outside magnetism, all being utilized 
within for useful work. 

The size ot field-magnets is dependent on the armature. 


FORMS OF FIELD MAGNETS. 


33 


The capacity of a dynamo lies in its armature, and for that 
the first calculation is made. Afterwards suitable field-magnets 
can be designed. An early error in dynamos was to use very long 
“cores” At present they aye very short and the magnetic yoke 
massive. The diameter of the “cores” for most purposes should 
be two-thirds or four-fifths of the diameter of the armature, and 
their length about equal to the diameter of the armature. 

An important consideration in the design of magnets is to 
keep in mind accessibility to the armature. It is not advisable 
to remove or replace an armature endwise, but the field-magnets, 
in part or whole, should be easily removed, and leave the 
armature open for inspection or removal. Tne reader will 
remember that in selecting his form of field-magnet the best 
results will be obtained from those having the most compact 
form, the greatest cross section, the softest iron, and the fewest 
joints. A larger variety of forms of field-magnets might be 
shown in this chapter, but the author thinks he has shown 
enough to enable the reader to form a fair idea of the ordinary 
types. One thing must not be forgotten, that the air space be¬ 
tween the pole-pieces and the armature core should be made as 
large as possible in area and as thin as practicable. 

The pole-piece projections should not be too near to each 
other, nor should they be too near other iron parts, on account 
of leakage. They should also be rounded off on their outer 
edges, for these projections are often the most intense parts of 
the field-magnets, and the waste of magnetism by leakage from 
them is, in some cases, enormous. 

In conclusion.—No rule can be laid down for selecting 
the best form of field-magnets. The best for one purpose is 
not the best for all. Some. designs are best made of cast-iron, 


* 


3 








34 


DYNAMO-ELECTRIC MACHINERY. 


others of wrought iron, and then, again, best results may be 
obtained from the composite form, having cast-iron polar masses 
and wrought iron bobbins. The large machines will need a 
number of poles, while in the small machines a simple circuit 
will be the best. 



armatures. 


35 


CHAPTER V. 

ARMATURES. 

Every dynamo-electric machine has an “armature.” Its 
purpose is. to convey the magnetism from one pole-piece to the 
other. This name is borrowed from the phraseology adopted in 
the days when horseshoe permanent magnets were invented. 

The soft piece of iron called the “keeper,” across the poles of 
a permanent horseshoe magnet is familiar to everybody. This 
is technically called an armature. Armatures of dynamos are 
generally cylindrical and have imbedded in them or laid upon 
theii suiface insulated copper wires, for conducting the currents 
of electricity which are generated when the armature revolves. 
The iron centre upon which the wire is wound is called the 

“core.” The whole is generally mounted upon a suitable shaft. 
One of the earliest armatures is the Siemens, or shuttle form. 
It consists of a cylinder of wrought or annealed cast-iron, which 
is grooved on both sides and the recesses filled with wire 
wound back and forth. To each end is screwed a brass head, 

into which short shafts are fitted. These shafts, besides support¬ 

ing the armature in position, carry the driving pulley and the 
commutator. The commutator has but two parts, to which 
(after being carried through a hole in the shaft) the two ends 
of the coil sit c attached. This form of an armature is very 







DYNAMO-ELECTRIC MACHINERY. 


36 

energetic and is well adapted to small dynamos for intermittent 
work. When run continuously this form heats, on account of 
the large mass of iron in the “ core.” 

The' two forms of armature most commonly met with in 
practice are the Gramme ring and drum, or variations of them. 
The Gramme ring armature consists of a ring or hollow cylin¬ 
der of iron, upon which the wire is wound. Instead of going 
completely around the outside of the armature, each turn of 
wire goes through the opening in the middle and thence back 
to the outer surface again. On an armature of this description 
each coil is wound by itself and is not overlapped by any of 
the others, consequently, if repairs are necessary at any time it 
is easy to get at the particular coil where the fault exists with¬ 
out disturbing any of the other coils, and this is often an 
important point, especially where the armature is wound with a 
large number of turns of fine wire. The coils, being each one 
open to the air, get better ventilation, thereby reducing the heat 
generated in the wire and core of the armature. On the other 
hand, the wire which passes through the middle of the armature 
is “ dead,” so far as to exciting an electro-motive force, and it 
does not help, but adds a wasteful resistance. 

The ring armature is more difficult to wind than the drum 
armature, as the wire must be passed through the middle for 
each turn. The cross section of the ring armature core is also 
necessarily smaller than a drum armature of the same dimen¬ 
sions, therefore its magnetic resistance is greater. In a general 
way we may say that the ring armature is better adapted for 
machines designed to give a constant current and a high poten¬ 
tial, while a drum armature is the proper kind to use for 
constant potentials and large currents. The core of a ring 


ARMATURES. 


37 


armature can be made in several ways. It should ?iever be a 
solid piece, on account of the eddy currents which would be 
induced in it and cause it to heat. It might be made of a flat 
ribbon of sheet iron, wound up to form a cylinder, but this 
will have, to a smaller degree, the same objection as the solid 

core. It is frequently made of iron wire wound on a 

“former” of wood, and shellacked and bound with tape to make 
it keep its shape. This method has many advantages; it is 
cheaply and easily done, and gives good results, and unless one 
has special facilities for doing the work, is probably the best. 

A core of this sort, however, is slightly inferior, considered as 

a magnetic conductor, to one made of discs or flat rings of sheet 
iron. Magnetism alwa}s shows a preference for running along 



figure 25. 

the gram of the iron, and it will have more difficulty in get¬ 
ting out of the centre of a core made of wire, (where it will 
have to go at right angles to the grain and besides, have 
numerous air gaps to leap across), than it would to get out of 
a similar core made up of discs. A ring armature with a core 
made of iron wire is shown in kiguie 2^. 











3S 


DYNAMO-ELECTRIC MACHINERY. 


If a core made of rings cut from sheet iron is used, some 
means must be devised to hold them together. This may be 
done by a bolt or screw through them from end to end, or 
they may be held by the “spider” by which they are attached 
to the armature shaft, as shown in Figure 26 



There is no need of paper or any other insulation between 
the discs; the black oxide of iron on the surface is sufficient. 
The danger of heating is not so much from the small currents 
in the discs jumping across from one to another, as from the 
lines of magnetic force going through the armature slantingly. 
The length of the armature core should equal the width of the 
pole pieces, in order that the lines of force may go straight 
from one pole to the other. The wires on the armature must 
always be very carefully insulated from the core. On small 
machines this may be done by covering the armature core with 
two or three layers of wrapping paper, sticking it on with 
shellac. On large machines a layer of canvas should be placed 
between the papers to lessen the liability of breaking through 
on corners and sharp edges. For if this insulation should rub 
through or be crushed at one point, the whole electro-motive 
foice of the machine will act at another point, thereby bursting 



























ARMATURES. 


39 


through the insulation and causing the current to “jump” 
through to the core and thus burn out the armature. 

In regard to the necessity for some means of holding the 
armature coils in place, there is a diversity of opinion. Some 
manufacturers wind coils on a smooth core and trust to friction 
and good luck to hold them where they are placed, while others 
use various methods to hold them there. The strain on these coils 
is caused by the resistance against which the armature must be 
turned, and the effect is very much the same as if a brake 
was applied to the surface of the armature to prevent its rota¬ 
tion. One method employed to prevent the coils from slipping 
is to bore holes in the external surface of the armature core 



close to the ends between the coils, and drive pegs, either of 
wood or iron, into them, as shown in Figure 27. If iron pegs 

are used they must be insulated. 

Another, but more expensive way, is to make the discs 
which form the core of the armature like a toothed wheel. 

See Figure 28. 





4 ° 


DYNAMO-ELECTRIC MACHINERY. 


When these are put together to form the core the projec¬ 
tions will make ribs, running the length of the armature core, 
between which are channels in which the wire may be wound. 
This not only giYes a solid construction, but also has the ad¬ 
vantage of reducing the magnetic resistance of the air space. 



A good proportion for cylinder armatures is for the diameter 
to be two-thirds its length. In the ring form the diameter 
should be about twice its length. 

A safe calculation in winding drum armatures is to reckon 
one volt for every two feet of active wire. Very small machines 
are not so efficient as large ones. A “ core ” seven inches out¬ 
side diameter, five inches inside, and four inches long, wound 
in forty-eight sections with No. 15 wire will furnish a current 
of about 80 volts and 15 amperes. The wire must be two 
layers deep, and the armature driven at about 2200 revolutions 
per minute. A field-magnet of style shown in Figures 15 or 
22 would be suitable for the armature described above. By 
using wire one-half the size and making twice as many turns, 
a four-pole field-magnet can be used. Twelve pounds of No. 
12 wire will be sufficient for the field-spools. If it is necessary 








ARMATURES. 


4 1 

to piece wires in the armature coils, the joints should always 
be soldered, being careful not to make a lump in the winding, 
which will be unsightly or in danger of touching the pole-pieces. 

The last operation is to put on the binding wire. This is 
to prevent the winding from flying out when the armature is 
run at a high speed. The number of bands needed will depend 
upon the length of the armature. A small armature may need 
only one, while a large one will need three or more. These 
bands should be about one-fourth or one-half of an inch wide, 
wound on tightly and soldered at intervals their whole width. 

The connections to the commutator can be made by either 
screws or solder, but perhaps best by both. In some cases it 
is considered better to solder the wires to flat strips, which may 
be bent around the wires to make a better connection, and then 
screw and solder these strips to the commutator bars, their 
shape allowing them to make a better contact than the round 
wires. . 

After an armature is finished it must be properly balanced, 
otherwise it will be liable to vibrate when running at a high 
speed, which will be augmented by the consequent unbalanced 

pull of a strong field on the armature, due to the core vibrat¬ 
ing so as to come nearer to one pole-piece than the other. 
If this vibration becomes too violent it may cause the armature 
to abrade its surface on the pole-pieces, thereby cutting its 
bands, often resulting in short circuiting and total destruction 

of the armature. To balance an armature, place the two ends 

of the shaft upon two parallel metal rails (or knife edges). 

The armature will usually come to rest in some particular 
position, which shows that the upper side needs more weight. 
If badly out of balance some pieces of lead can be wedged 









4 2 


DYNAMO-ELECTRIC MACHINERY. 


under the binding band. If only a little out of balance add a 
little solder to the binding wire on the light side, until the 
armature will stay in any position that you may place it. 

Properly made, there is no electrical difference between the 
drum and ring forms for armatures. Where a narrow machine 
and high speed is desirable the drum form is the best; while 
for a short shaft and slow speed the “ring” offers valuable 
advantages. For further information about “armatures” the 
reader is referred to the author’s book, “Armature and Field- 
Magnet W inding.” We have devoted all the space in this book 
to this subject that can be spared, and in the following chap¬ 
ters explicit directions and full working drawings will be given 
to enable the reader to wind the armature of each machine, 
therein described, to obtain the output for which it is designed. 


HOW TO MAKE A TOY ELECTRIC MOTOR. 


4^ 


CHAPTER VI. 


HOW TO MAKE A TOY ELECTRIC MOTOR. 

COMMON weakness of toy motors of any kind is their 



±\ brevity of life. Miniature steam engines, being made of 
soft metal, soon wear out, and electric motors have some deli¬ 
cacy of construction that is easily deranged. 

In this chapter an attempt is made to describe a motor of 
such size and substantial design as not to be easily injured, and 
of such simplicity that a boy may quickly build it. The 
mechanism is self contained. Figure 29 shows the assembled 
machine in plan and elevations. 

The field-magnet is an iron casting, although a piece of 
wrought iron could be bent to the necessary shape. Figure 30 
represents the detail of this part. The central portion, called the 
core, is round where the winding is to be located, but divided 
into two spaces by a collet that serves to hold one end of the 
armature shaft. At each extremity of the winding space rises a 
rectangular pole-piece, the upper ends of which are tapped 
“8-32” for screws that hold the upper bearing for the shaft in 


This bearing consists of a flat strip of sheet brass one- 


eighth inch thick and one-half inch wide, as shown in Figure 
31. The end holes are drilled large to allow a little adjustment. 
Figure 32 shows the revolving parts, consisting of a cross-shaped 
casting for the armature, a piece of square brass for the 


iron 






44 


DYNAMO-ELECTRIC MACHINERY, 




FIGURE 29. 


































































































































































































































HOW TO MAKE A TOY ELECTRIC MOTOR. 


45 



commutator, and a piece of one-eighth inch steel or iron wire for 
the shaft. A wire nail will answer for the latter. Horns on the 
ends of the armature increase the scope ot the field. The 
armature and commutator are to be tightly driven on the shaft; 
it will be noticed that the sides of the two are not exactly 
parallel; the commutator is given a little u lead.” 

In the assembled drawing the location of the single brush 
is shown. It consists of a piece of thin and springy sheet 
copper or brass. It should be not over one-hundredth of an inch 
thick, one-fourth of an inch wide, and three and one-half inches long, 
with the exterior end soldered to a wire that leads to one binding 
post. A piece of thick paper for insulation is wrapped one 
turn around the brush where it crosses the cast-iron pole-piece. 
A clamp of brass or iron one-sixteenth of an inch thick, five-sixteenths 
of an inch wide, and three-fourths of an inch long, with the aid 
of a three-eighths 6-32 screw, holds the brush in position. 




















































































4(5 


DYNAMO-ELECTRIC MACHINERY. 


























































HOW TO MAKE A TOY ELECTRIC MOTOR. 4* 

After the mechanical part of the work has been completed, 

the builder can easily add the electrical equipments. The wind¬ 
ing can be quickly done in a lathe. No. iS wire, either single 
or double covered, is suitable. Provide about one-half pound. 
Strip the insulation oft for a distance of four or five inches and 
begin winding one of the spaces. When it is filled, continue 
into the other until that also is filled, then connect to the second 
binding-post; it will be well to wrap a turn or two of thin 
paper around the iron in the second coil, as there should be no 
connection with the iron except at the very beginning. The 

electrical circuit will be finally as followsEntering at the 

binding post just mentioned, the current will pass around the 
field-coils, magnetizing the iron, then enter the iron through the 
bared portion, to the armature, shaft, the commutator, brush, 
and by the wire to the other binding-post to the battery. The 
brush and commutator must be so adjusted that when the arma¬ 
ture is in the position shown in Figure 29 the contact has just 
been broken. In starting the motor, a little push must be given 
the armature to get it off the “dead center.” When it has 
turned a little way, one corner of the commutator will touch 
the brush, make a contact and magnetize the field. T e arma¬ 
ture prongs that are approaching the poles will be vigorously 
thrust around; but at the instant the two pieces of iron are 
nearest together the commutator will have broken its connection 
and the field-magnetism vanished; momentum will carry the 
armature along until a second attraction has taken place. A 
speed of a thousand revolutions per minute can be easily attained 
by using a bichromate battery for a source of current. If sal- 
ammoniac or gravity cells are used, No. 24 wire will be more 
suitable than No. iS for the winding. 







4 S 


DYNAMO-ELECTRIC MACHINERY. 


On the upper end of the shaft a simple wooden pulley can 
be driven. This motor may be used to run small toys, fans, 
etc., or with a little ingenuity can be fitted to a small toy boat 
or electric car, but no appreciable amount of power can be 
derived. The only object is to make a device that will u go,’* 
and to illustrate in a practical way the principle of the electric 
motor. 


HOW TO MAKE A SMALL DYNAMO. 


49 


CHAPTER VII. 


HOW TO MAKE A SMALL DYNAMO. 



HE dynamo and motor are theoretically identical, but in 


. practice a slight difference is made in the design, especially 
of small machines. 

This difference is mainly due to the necessity of having 
the magnetic circuit or path for the lines of magnetic force as 
perfect as possible in a dynamo, since it must itself supply the 
energy to excite the fields, and the strength of the fields regu¬ 
lates to a great extent the amount of energy the dynamo is 
capable of delivering. With the motor, this is different, for 
while it is necessary that the magnetic circuit be good, if a high 
efficiency is desired it is by no means necessary to the running 
of the motor since the energy to excite the fields is taken from 
an outside source, which, it is supposed, is capable of meeting 
all the demands which will ordinarily be made upon it. 

It follows, therefore, that in order to have a dynamo capa¬ 
ble of doing much, we must have perfect fitting joints between 
the iron parts of the fields and as little clearance as possible 
between armature and pole-pieces, and all this means good work¬ 
manship with good tools. We would, therefore, advise the 
amateur who does not possess these latter essentials to have the 
lathe work and planing done in some machine shop, as there is 


4 



50 


DYNAMO-ELECTRIC MACHINERY. 


not much of it to do, and the dynamo will work in a much 
more satisfactory manner than if the machine work is botched. 

The shaft of our armature should be made of machine steel, 
one-half inch in diameter and nine and one-half inches long. 
The core of the armature is made of disks of sheet iron three 
inches in diameter and punched out at the centre just large 
enough to fit tightly on the shaft. If these disks are made of 
ordinary sheet iron the black oxide on the surface is enough to 
insulate them from each other. They can, however, be made of 
tin plate, in which case it will be necessary to place pieces of 
thin tissue paper between them. See Figure 33. 



figure 33. 

Drill a one-sixteenth inch hole through the shaft, three and 
one-eighth inches from one end, and another three inches from 
this hole. Place a piece of one-sixteenth inch wire, one inch 
long, through one of the holes, and then put the disks upon the 
shaft, driving them tight against the wire, and when you have 
put on enough to make a compact cylinder three inches long, 
drive a piece of wire through the other hole to keep the disks 
in place. The core must now be insulated by covering it 
smoothly with two thicknesses of heavy brown paper, stuck on 
with shellac. The armature shaft, also, should be treated this 
way for an inch and a quarter from each end of the core. Be 























































































HOW TO MAKE A SMALL DYNAMO. 


5 1 


careful to cover up every part of the core, as it will be the 

source of much annoyance if a contact develops between it 
and the wire. 

Divide the circumference of each end of the core into ten 
equal parts, being careful to have the divisions at one end 
exactly opposite to those at the other. At each division mark 
saw a slot one-half inch deep across the corner. Into each of 
these slots drive a piece of stiff card-board or ebonite, as shown, 
lea\ ing it to project about a quarter of an inch, and trimming 
it oil' even with the wire after the armature is wound, as in 
Figure 34. 


W I 



FIGURE 34. 


We are now ready for winding, and for this purpose will 
need about two and one-half or three pounds of No. iS double 
cotton covered copper wire. The winding we shall adopt is 
called the Siemens winding. 


Begin at the end where the shaft is shortest and wind on 
the wire lengthwise on the core. The wire must be wound 


smoothly and tightly, but must be bent aside at the ends to 
allow for the displacement of the shaft. Be careful not to injure 
the insulation on the wire. Each coil, if packed tightly, should 
have seventeen or eighteen turns. See Figure 35, 

As soon as one coil is completed do not cut the wire but 
simply leave a loop two or three inches long and begin winding 
the next coil in the same direction. Begin the winding of each 



















5 2 


DYNAMO-ELECTRIC MACHINERY. 


coil on the right-hand side of the division and wind to the left, 
and begin the next coil where you leave off on the last. Give 
the loop a twist close to the core to prevent the first few turns 
of the wire on the new coil from getting loose. Before begin- 



FIGURE 35. 

ning a new coil cover the last one at the ends of the armature 
where it will be crossed by the new coil with a piece of cotton 
cloth, laid on with thin shellac. When you have wound on five 
coils you will have occupied each of the divisions. Give the 
wire you have wound on a good coat of thin shellac and cover 
it with a piece of cotton cloth. Now continue and wind over 
these coils five more in the same way, observing the same pre¬ 
cautions, and when you have finished cut off the wire and twist 
the end with the free end of the first coil. Shellac the last 
winding thoroughly. 

Our dynamo is intended to run at a pretty high speed, so 
to prevent the wires flying out by centrifugal force and rubbing 




HOW TO MAKE A SMALL DYNAMO. 


53 


against the pole-pieces, we bind them down by half a dozen 
turns of thin brass wire at a third of the length of the armature 
from each end. In order that the brass wire may not cut 
through the insulation of the wire and short circuit it, we place 
two thicknesses of heavy brown paper where the binding is to 



Brass 

Vulcanite. 


FIGURE 3 6. 

be, and if mica is obtainable a thin layer of that, too, and then 
wind the brass wire on tightly; a dozen turns at each end will 
do, soldering the wires together every inch or so. 



























54 


DYNAMO-ELECTRIC MACHINERY. 


Next in order is the commutator. The backing should be 
made of vulcanite or fiber, but if this is not obtainable a piece 
of good hard wood, not liable to crack or shrink, can be made 
to do. If wood, it should be well paraffined. 

Figure 36 gives the dimensions of the commutator complete. 
If the brass hub be knurled where it goes through the vulcanite 




FIGURE 37. 

it will keep it from slipping. A one-eighth inch machine screw 
through the brass hub will keep it from slipping on the shaft. 

The commutator bars are made from a ring of brass, which 
is first screwed to the vulcanite backing by twenty screws, the 




































HOW TO MAKE A SMALL DYNAMO. 


j5 

heads of which are countersunk just level with the surface of 
the brass. The ring is then cut radially into ten equal parts, 

while it is still screwed down. Put the commutator on that end 

/ 

of the shaft where the ends of the coils are left sticking out, 
and placing it with its end seven-eighths of an inch from the 
end of the shaft, and the segments of the commutator opposite 
the loops of wire, and set the set-screw; now pull one of the 
loops over the middle of the end of the bar opposite to it and 
cut it off so that it just reaches past the bar. Bare the ends 

of the wire and solder them together to the end of the bar. 

Do this with each loop and your armature is complete except 
balancing. 

To do this place two straight edges in a horizontal position, 
leveling them carefully, and placing them at such a distance 
apart that the ends of the armature shaft will rest upon them. 

If it tends to roll to any one position it needs some more weight 
on the top side of the position where it comes to rest. Put on 
a little solder and repeat the operation until it will stay in any 
position on the straight edges. 

The dimensions of the iron parts of the fields are given 
in Figure 37. 

The pole-pieces A could be cast-iron, but the shape is so 

simple that they can easily be planed up from a slab of wrought 
iron, and will give much better results. The field-cores B are 
simply pieces of wrought iron turned to size and tapped for 
half-inch bolts. The faces ff of the pole-pieces and the ends 
e e of the field-cores which are to join them must be accurately 
surfaced. The diameter of the bore b was intentionally omitted, 
since no two inexperienced persons will wind an armature alike, 
and it would be impossible to predict exactly its diameter when 






5 6 


DYNAMO-ELECTRIC MACHINERY. 


finished, and as the bore must be just large enough to allow the 
armature to revolve and clear. The diameter of the bore can 
best be found by calipering the armature. 

The field-cores must have washers of some sort, preferably 
fiber, to hold on the wire. They should drive tightly on to 
the core and have an external diameter of three inches, and be 
one-eighth of an inch thick. Put one of these washers on each 
end of the field-cores, letting the core project just a trifle, say 
one-thirty-second or one-sixty-fourth of an inch. Insulate the 

core by wrapping two thicknesses of heavy brown paper around 
it between the washers. Bore a one-sixteenth inch hole through 
a washer on each core, close to the core and through this from 
the inside put six inches of the wire with which you are going 
to wind your fields. Bend it where it comes through to hold 
it, and putting the core in a lathe start it to revolving and wind 
on the wire. Be careful that it is wound on closely and tightly. 
After winding on one layer wrap a piece of paper around it 

and wind the next layer over this. Wind on ten layers of the 

same kind of wire you used for the armature. When you begin 

to wind on the next to the last layer, tie a piece of string to 
the first turn and let the ends hang out, and when you finish 
the last layer, before cutting off the wire tie the last turn down 
with the string, and cut the wire about six inches from the tie. 
Wind both fields in the same direction; we will say begin at 
the left-hand end and wind on the wire with the lathe running 

backwards. The supports from the ends of the armature should 

« 

be cast of brass or moderately hard gun metal — under no cir¬ 
cumstances of iron. The dimensions are given in Figures 38 
and 39. 


Oil hole. 


HOW TO MAKE A SMALL DYNAMO. 


57 




FIGURE 39. 
































































































58 


DYNAMO-ELECTRIC MACHINERY. 


An oil hole should be bored in each bearing and an escape 
for the waste oil below, so that it may not get upon the pole- 
pieces and thence to the armature. 

The brushes and brush holder next demand our attention. 
The yoke had best be made of vulcanite or fiber, though good 



figure 40. 

hard wood will do. The dimensions are given in Figure 40. 

The brush holders are shown in shape and size in Figure 
41, and are to be made of brass. 



YVoV&cv- 





FIGURE 41. 

The piece t is soldered to the part «, leaving the slot 5, 
through which the brushes are passed and held by the screw. 

































HOW TO MAKE A SMALL DYNAMO. 


59 


The brushes themselves are strips of thin copper five-eighths of 
an inch wide and one and one-half inches long, three or four 
pieces going to make one brush, according to the thickness. 
They are soldered together at one end to keep them from slip¬ 
ping. The pulley is made of cast iron or brass, according to 
the dimensions given in Figure 42. A collar, to be placed 




FIGURE 42. 


between the armature winding, and bearing on the pulley end 
of the shaft, is made of iron one-fourth of an inch thick and 
three-fourths of an inch in diameter, and has a set screw to 

hold it to the shaft. 

We are now ready to set up the dynamo. Bolt the bottom 
pole-piece to the ends of the fields where the wires come out. 
Let the inside wires of the fields come out on what you have 
decided to make the commutator side of the dynamo, and cut 
grooves in the bottom pole-piece for the wire to lay in. The 
wire should, by the way, be tapped where it touches the iron. 

Bolt on the. top pole piece and one of the bearings. Put 

the armature in position and bolt on the other bearing. A 

wooden base 9x10x1^ inches should be provided and screwed 
























6o 


DYNAMO-ELECTRIC MACHINERY 


to the bottom yoke of the fields. On this, place six binding 
posts, two for the armature cable and one for each of the ends 
on the field winding. A diagram of the connections is shown 

n Figure 43. 



Binding post A is connected to the outside end of the left 
field, B to the inside end, C to the left-hand brush, D to the 
right-hand brush, E to the outside end of the right-hand field, 
F to the inside end. The brushes should be connected to the 
binding posts by means of flexible cables. One strand of the 
twin conductor, such as is used to suspend incandescent lamps 
will do very well. The brushes should be set so that their ends 
bear firmly on the commutator. Turn the armature until one of 
the commutator slots is even with the end of one brush and set 
the brush so that its end is parallel with the slot. Then keep¬ 
ing the armature and brush yoke in the same position set the 
other brush in the same way on the opposite slot. It is impor¬ 
tant that the brushes be set accurately, for if badly adjusted there 
will be sparking at the commutator, which will injure both brush 
and commutator. 



























HOW TO MAKE A SMALL DYNAMO. 


6 I 


Before starting up the machine the fields must be magnet¬ 
ized. Connect the binding post B and E and put a current 
from a battery or other source of electric energy through the 
fields from A to F. Then remove the connection between B 

and E, and connect B to C and D to E. Belt your dynamo, 
to your source of power, and let it be run at a high speed, 
the higher the better within certain limits, say up to 2^00 or 
3000 revolutions a minute. If no other source of power is 
available, a sewing machine could be used by disconnecting the 
works from the fly-wheel and belting from that directly to the 
dynamo. The belt should only be tight enough to prevent slip¬ 
ping, as anything beyond this will waste energy in heating the 
bearings. 

If you have a small steam engine the dynamo can be made 
to regulate, automatically, for a constant current, supposing your 
steam pressure can be kept constant. This is done by simply 

leaving off any governing device whatever from the engine and 
letting it run fast or slow, according to the demands of the 
dynamo. Of course nothing but the dynamo must be run from 

the engine. The dynamo must be run left-handed when you 
face the commutator. If the dynamo does not begin to generate 
immediately when the outside circuit from A to F is closed, 
gradually cut down its resistance until it does generate. Then 
shift the position of the brushes until there is no sparking at 
the commutator. 

The method spoken of above for securing a constant current 
can be applied to running lamps in series. The lamps can be 
cut in or out of the circuit without changing the brilliancy of 

the rest, since the dynamo under the conditions given, is self- 
adjusting for constant current. It sometimes happens where a 




DYNAMO—END VIEW. 































































































































































































HOW TO MAKE A SMALL MOTOR 


6 3 



DYNAMO —SIDE VIEW 





































































































































































6 4 


DYNAMO-ELECTRIC MACHINERY. 


greater out-put from the dynamo is desired, that it is necessary 
to separately excite it. To do this disconnect B C and D E, and 
connect B E. Connect the battery or whatever you intend to use 
to excite the fields to A and F. 

The battery should be capable of sending three or four 
amperes through the fields. The external circuit is run from 
the terminals C and D. The out-put can be nearly doubled by 
this method. This is also, the method to use where a constant 
potential is desired, but in this case the speed must be kept 
constant, and the engine or whatever supplies the energy, have 
some governing device. The current taken from the dynamo 
ought not to exceed five or six amperes. The circuit may go 
higher for short intervals, but it is not good practice to let it 
do so. 


HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


65 


CHAPTER VIII. 

HOW TO BUILD A ONETOURTH HORSE POWER MOTOR 

OR DYNAMO. 

N O less accurate workmanship is required in the construction 
of a small dynamo than in one of a larger size. However, 
in this chapter is described a machine of such size and 

arrangement of parts as to be within the reach of amateurs’ 

tools, yet capable of continuous and efficient service. It can be 

used as dynamo or motor, series, shunt, or compound wound, 
for any potential not exceeding iio volts. Figures 44 and 45 

show the complete machine in side and end elevations. 

For convenience the description will be divided as follows: 

1. Field magnet and frame. 

2. Armature, shaft, and pulley. 

3. Bearings. 

4. Commutator. 

Brushes, holders and yoke. 

6. Winding. 

7. Connections. 

8. Testing and using. 

The Field Magnet and Frame consists of two cast iron “pole 
pieces” united by a wrought iron “core”. Referring to Figure 46-(b), 
it will be seen that the castings are apparently alike, but the 
patterns must be so made that the arms for supporting the 
5 













66 


DYNAMO-ELECTRIC MACHINERY. 


bearings will come on reverse sides, so that when the two are 
placed facing each other, both long arms will be on the com¬ 
mutator side and both short arms on the pulley side. 

Provided with the castings, the holes for the core should 
be bored out smoothly to 2 inches in diameter. For doing this 
the castings may be either bolted to the traveling carriage of a 
lathe, and a boring bar inserted, or to a face plate, using 
a rigid inside boring tool. If possible finish with a reamer. 
Drill, tap and counter-bore for the seven-sixteenths inch screw 
“a” on the bolt and screw list, Figure 47. The slots at the 
bottom, which may well have been cored part way, can now 
be extended through with a hack saw. The core is to be of 
wrought iron, seven and three-sixteenths inches long, smoothly turned 
to two inches in diameter. If what commonly known as “cold 
rolled” steel is available, no turning will be necessary. This 
quality of steel is very soft and quite as good as wrought iron 
for magnetic purposes. 

Put one pole piece on. the core, tighten the clamping 
screw; drill a one-fourth inch hole through the cast-iron into the 
steel and drive in a steel pin about three-fourths inch long. 
These two parts will then be permanently attached. Slip on the 
other pole piece, see that the protruding arms are parallel, 
tighten in place, and drill a one-fourth inch hole in the end, 
so as to be half in the core and half in the pole piece, in the 
location as shown, and drive in another pin. This method 
locates the two parts definitely, but allows easy removal of one 
pole piece for placing the field spool. 

The boring of the ends of the arms and the field may 
now be done. Bolt the structure as now assembled to the car¬ 
riage of a screw cutting lathe. With a boring bar between 


























































































68 


dynamo-electric machinery. 






























figure 46 (a). 






























































































HOW TO BUILD A 1-4 H. P. MOTOP OR DYNAMO. 


69 







VO 


w 

D 

O 

>—1 


































































7 ° 


DYNAMO-ELECTRIC MACHINERY. 


centers, take first a slight chip, at slow feed. If carefully done, 
there will be no danger of breaking off the arms, but if con- 
venient some sort of supports can be devised to brace the long 
ones. The finished diameter should be three and one-sixteenths 
inches. Drill and counterbore the holes in the arms for screws 
“b”; drill and tap the two in the top for screws u c”; drill the 
four in the feet for screws “d”. The removal of sharp coineis 




i 






FIGURE 47 . 



or fins on the castings will complete the machine work on the 
field magnet. 

Armature , Shaft and Pulley. The armature .is of the 
toothed drum type, built up of laminations of sheet iron. Fig¬ 
ure 48, «, shows one of these sheets. If punchings of this description 
cannot be otherwise obtained, the builder may proceed as follows: 
From stove pipe iron cut three and one-eighth inch squares. 
Enough should be cut to make a thickness two and one-fourth 













































































HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 7 I 

inches when tightly clamped together. Cut the corners so as to 
make the sheets octagonal. Clamp them between plates of one- 
fourth or three-eighths inch iron and drill a five-eighths inch 
hole as near the center as possible. Put in a short five-eighths 
inch turned bolt and screw on the nut. Remove the other 
clamps and turn the mass to a diameter of three .inches. 

Without disturbing the center bolt, put the cylinder thus 
formed in a milling machine or gear cutter and saw out the 
the sixteen slots as shown, one-fourth inch wide and three-eighths 
deep. 

Part of the work on the shaft may now be done. Procure 
a suitable length of cold rolled steel, five-eighths inches in diam¬ 
eter, center it in a lathe, with the aid of a back rest, and turn 
it, excepting the space three inches long in the centre, to nine- 
sixteenths inch in diameter. On the ends of that space cut 27 
threads per inch for a distance of three-eighths inch. Cast-iron 
flanges or “ heads,” for screwing on these threaded portions, are 
clearly shown at “ b ,” Figure 48. Screw one of these tightly 
in place and slip on the punchings. It will be necessary to put 
a piece of iron, or brass one-fourth inch thick and about three 
inches long in one of the grooves in the sheets, to keep the 
teeth matched. With this bar still in place, tightly screw 
on the other head, using a spanner wrench with pins en¬ 
gaging in the two small holes as shown. By oiling its 

surface and threads, this may be easily done without allowing 
the sheets to slide on each other. Replacing the armature in 
the lathe, it will probably be found that the shaft does not 
run true; this is due to the fact that sheet iron cannot be 
procured of an exactly uniform thickness, and the shaft has 

had to bend to compensate for the difference. With a lever 












7 2 


DYNAMO-ELECTRIC MACHINERY 



FIGURE 48. 









































































































HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 

spring the shaft until it runs true, and complete the 
to the required dimensions. Leave the portions for the bear- 





figure 49. 


ino-s about one-hundredth inch large to allow for final fitting. 
Put in the small pin for holding the commutator in position. 


73 

turning 




























































































































74 dynamo-electric machinery. 

After turning and fitting the pulley, a No. 30 drill may be 
run in on the end, half in the pulley and half in the shaft. 
Use a piece of one-eighth inch steel wire for a key and so 
locate the set screw as to hold the key in. Figure 48 shows 
the completed structure. 

Bearings. In order that magnetism may not be diverted 
from its useful path, the bearings should be of brass, or 
some similar material. The construction of these is given in 
Figure 49. For the pulley end a longer bearing is provided 
than for the commutator end, and the center so located as to 
carry the pulley at a safe distance from the ends of the arms. 
Proximity would encourage leakage of magnetism. 

Chuck the castings, bore out the cored holes, and ream 
to three-fourths inch in diameter. Mount them on an arbor and 
turn the ends to three and one-sixteentlis inches in diameter 
and on the commutator end casting cut the straight portion 
for the yoke bearing one inch in diameter for a distance of 
one-fourth inch. Lay on the oil-well covers and drill for the pins 
on which they hinge. Set the bearings in position between 
the ends of the arms; it will ensure their alignment if a 

4 

three-fourths inch arbor is inserted, long enough to extend through 
both. A one-fourth inch drill may be run through the pre¬ 
viously drilled holes in the arms for about one-eighth inch into 
the brasses. Drill one-half inch further with a No. 8 drill and 
tap out 14-20. The screws “b” may now be inserted and arbor 
removed. 

Quite a variety of materials are suitable for the bushings 
or “linings” for the bearings. Brass, gun metal, graphite, 
cast iron, babbitt metal and lignum vitae are used. Gun metal 
is in good favor. Drill out the castings, ream them to one- 


HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


75 

half inch in diameter, mount them on an arbor, turn the out¬ 
side and ends to size. The oil groove may be cut with a 
round-nosed hand tool. It will be noticed that the linings are 



figure 50 . 

shorter than the castings into which they are to be forced. 
The purpose is to provide a surface for catching the oil that 
may be thrown from the shaft while running. Locate the 
linings so as to bring the armature in center of the hela, and 

































































DYNAMO-ELECTRIC MACHINERY. 


76 

allow about one-sixteenth inch for end motion; then drill 
through the bottom of the oil-wells and insert short pieces of 
brass tube. When occasion requires the removal of the bushings, 
these tubes may be driven entirely through and out of the way. 

Thick grease of about the consistency of lard is to be used 
for lubrication, and a little will last a long time. The warmth 
of the bearing will melt just enough grease to ensure proper 
oiling. 

Com?nutator . The construction of a commutator is often 
a Waterloo to an amateur, but the one here described is 
compact, durable and well insulated. A comparatively small 
lathe and easily obtained materials will suffice for its construc¬ 
tion. There are sixteen divisions, or “segments,” made of smooth 
copper, drawn wedge-shaped, or of filed castings to fit around 
into a complete circle; or a ring may be turned to the right 
size and then split into sixteen parts. The latter may be the 
more available method. 

Procure a piece of copper tube, or gun metal casting, that 
in the rough measures about one and seven-eighths inches 
outside diameter, fifteen-sixteenths inch inside, and seven-eighths 
inch long. Bore out the inside to one inch in diameter, mount 
it on an arbor and turn the outside to the dimensions shown 
at “a” in Figure 50. While still on the arbor, place it in a 
milling machine, slotter, or gear cutter, and saw it into six¬ 
teen segments. Let the saw be thin and cut within one-thirtv- 
second inch of the arbor. Fit strips of mica to the saw cuts, 
then finish cutting the segments apart. File off the burrs and 
assemble the segments and insulations into a circle. Secure them 
with a string or rubber band, and prepare the rest of the 
structure. 


FIGURE 51 










^j;2r£-9 




























































































DYNAMO-ELECTRIC MACHINERY. 


7S 

A piece of seamless brass tube, one and three-eighths inches 
long, three-fourths inch outside and nine-sixteenths inch inside 
diameter is to be threaded for a short distance at each end. 
Use a fairly fine thread, say twenty to the inch. File a slot 

one-eighth inch wide in one end to fit the pin that was located 

in the shaft. Tap two iron or brass nuts to match. Drill two 
holes in these thin nuts to allow the use of a spanner wrench. 
Screw one of these on tightly. Turn two vulcanized fiber discs 
as shown at “b” in Figure 50, and slide one on the brass 
tube; set the segments into the grove; put on the other disc, 
and screw on the other nut, but be careful not to let the seg¬ 
ments get “skewed” or strained into a spiral. 

Provision must now be made for getting electrical connec¬ 
tion between the segments and the wires that are to be wound 
on the armature. Insert an arbor in the commutator and tilt it 
on a wooden jig or frame to an angle of about 15 degrees. 
Prick-punch into the fiber, in sixteen places opposite the centers 

of the segments, and drill through the fiber with a No. 32 

drill; then continue through the segment with a No. 40 drill, 
and thread with a 4-36 tap. Brass rods, threaded 4-36, u e” 
Figure 47 may be screwed into these holes, care being taken 
not to let them extend through the segments and touch the 
tube. Bind some copper wire tightly around the segments to 
hold them in place, and remove the nut from the end farthest 
from the connection screws; take off the disc and clean out 
the chips of copper that may have collected. Reassemble the 
parts, remove the binding wire, and turn the surface of the seg¬ 
ments even, finishing with a piece of fine sand paper. 

5. Brushes , Holders and Yokes . Two .kinds of brushes are 
commonly used, copper and carbon, with appropriate holders. 








HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


79 


The same supports called “yoke and studs” will fit either. For 
the former, “planished” or hard rolled leaf copper about five- 
one-thousandths inch thick is to be cut in strips seven-sixteenths inch 



wide and two inches long. Enough to equal one-eighth inch 
thickness should be grouped together and soldered at one end, 
the other bevelled to an angle of 45 degrees, to fit the commu¬ 
tator. The holder is shown assembled and in detail in Fig 
















































































60 


DYNAMO-ELECTRIC MACHINERY. 


ure 51. There are two brass castings, a body “a” and shoe 

“b”; a clamp “c” of sheet copper, and thumb screw “d” of 
brass. The construction is such that the pressure of the screw 
binds both the brush and the holder securely. A slight loosen¬ 
ing of the screw will allow the holder to be tilted, and remove 
the brush from the commutator, without changing the adjustment. 

A suitable carbon brush holder is given in Figure 52. The 
brass body casting “a” is drilled at one end one-fourth inch in 
diameter, the same as the copper holder, but the other end is 
drilled seven-sixteenths of an inch. A presser “b” is made of 

steel or brass wire about five one-hundredths inch in diameter. 

The clamp u c” is also a casting, and serves to retain the short 

end of the spring. By turning the clamp one way or the other 

a variation of tension on the spring may be obtained, and the 
screw binds it and the holder in any desired position on the 
stud. The brush is itself a short piece of standard electric 

light carbon, with one end filed to fit the commutator the 

other with a groove for keeping the presser in place. 

Make the brush holder “studs” of one-fourth inch brass 
rod. See “a” Figure 53. One end is turned to three-sixteenths 
inch diameter and threaded 10-24. For the flange, a brass 

washer may be slipped on the three-sixteenths inch portion, 
soldered and turned true. “b” and “f” are brass, the washers 
“c” and bushing “d” are hard rubber; terminal clip “e” is 
sheet copper. 

It is necessary to provide some means of adjusting the posi 
tion of the brushes. This is accomplished by attaching the 
studs to a rocker or “yoke.” The construction is shown also 
in Figure 53. Bore out the center of the casting to fit on the 
turned portion of the bearing as previously noted; drill and tap 


HOW TO BUILD A 1-4. H. P. MOTOR OR DYNAMO. 


Sr 


ll 



6 


FIGURE 53. 





























































































82 


DYNAMO-ELECTRIC MACHINERY. 






for the thumb screw, and then saw the slot. The rounding 
ends should be finished so as to allow the studs to be firmly 
held and kept parallel with each other. 

Winding . Having completed the general mechanical 
parts of the machine, the builder will be ready for the more 
purely electrical. Preliminary to the placing of the wire, there 
must be the uninteresting work of suitably insulating the core. 
An amateur is liable to slight this part of the work. 

The winding easily divides itself into the two separate por¬ 
tions,—armature and field. Just what sizes of wire to use 
will depend on the voltage and current desired, but the same 
general directions will answer for all. As the running of 
incandescent lamps is a common application of even small 
dynamos, a winding for lighting three standard 50 volt lamps 
will be explained in detail, and sizes stated for various other 
potentials. 

First, insulate the core; sharp corners are to be filed off, 
and a thin coat of shellac put on, extending along the shaft also for 
one and one-half inches. Wind several turns of thin, tough 
brown paper around the shaft, gash the paper a little so that 
it will lap up on the heads for one-eighth inch. Cut a num¬ 
ber of discs of paper three and one-eighth inches in diameter 
with five-eighths inch hole, and some strips two and one-half 
inches wide of indefinite length. Slip on a disc over each 
head and shellac it on. When dry make a single radial cut 
between the teeth with a pair of scissors and turn the edges of 
the paper over the corners into the grooves. Start the strip of paper in 
the bottom of a groove, and pass it over a tooth into the next 
groove; press it well into the corners with a thin strip of 
wood, and then press it down into the next groove, and 



so on 




FIGURE 54. 








































































DYNAMO-ELECTRIC MACHINERY. 


s+ 

around the core to the starting place; cut the paper, buc do not 
lap the ends. Slit the overhanging edges and bend them so as 
to cover any exposed iron. Put another disc on the heads, 
slit and bend over their edges as before ; put another strip all the 
way around the core, in the grooves, but be careful to have the 
joints always in different places in successive layers. Four layers 
everywhere will be a sufficient amount. The paper should occupy 
only so much space that a three-sixteenths inch strip can be 
forced down into the insulated grooves. Use thin shellac freely 
as an adhesive and do not allow the paper to “pucker” 
anywhere. 

Provide a continuous coil of about one and three-fourths 
pound No. 22 (twenty-five one-thousandths inch in diameter) 
double cotton covered magnet wire. Rest the armature between 
lathe centers or on other convenient support, so as to be turned 
back and forth as the winding progresses. Lay the starting 
end of the wire through one of the grooves toward the commu¬ 
tator end. For the moment it may be twisted around the end 
of the shaft. Carry the continuation of the wire across the 
head at the pulley end, giving the core a half turn so as to 
bring the opposite groove on top; lay the wire in this groove 
but leave enough room in passing the shaft to allow for five 
more turns. Cross the head at the commutator end, at the 
same distance from the shaft back to the starting point, rotating 
the core back to its original position. Lay a second turn 
beside the first, then a third, and so on until six turns are on. 
This should make just one layer in the grooves. The wires 
may be smoothed down and firmly pressed into position with 
the aid of a chisel-shaped piece of soft wood. If the wires 
bulge a little in the grooves, pull them further away from the 




HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 



shaft, thus drawing them tight in other places. If sufficient 
room has not been allowed to get all the turns in past the 
shaft, a little stretching of this kind may provide space. Shellac 
these six turns and let them dry. “A”, Figure 54, shows this 

110 Volts. A. SO Volts. B 



Z5Volts. C. 



FIGURE 

first layer. Continue the winding 
six turns on the other side of 
shows this stage. Shellac again 

S 

third layer of six turns, passing 


7 Volts. B. 



in a second layer, and place 
the shaft. “B”, Figure 54, 
and when dry, wind on a 
the shaft on the same side 









































































86 


DYNAMO-ELECTRIC MACHINERY. 


as the first layer, only further out. See “C” Figure 54. A 
fourth layer goes on the other side, as shown in “D”, and also 
a half layer of three turns,— U E”. Make a loop in the wire 
about three inches long, twist the two together and lay the 

continuation in the groove next to the starting point. There 

will now be two slots a little less than half full of wire, and the 

twenty-seven turns will be so spread over the ends of the 

armature as to be but one layer deep where they pass the 

shaft. Wind twenty-seven turns in the next slot and its op¬ 
posite. These wires will cross the first wire at a slight angle; 
bring out a second loop and wind twenty-seven turns in the 
third slot and its opposite, and so on around until each of 
the slots have twenty-seven wires in them and eight loops are 
made for connecting to the commutator. Continue a ninth 
coil of twenty-seven turns on top the first coil; bring out a ninth 
loop, and wind a tenth coil of twenty-seven turns on top the 
second coil, and so on until the sixteen grooves have fifty-four 

wires each and fifteen loops are protruding. Cut the wire and 
twist it to the starting end. This will give a sixteenth loop. 
No cut is to be made during the entire winding up to this 
point. Trim off all superfluous insulation on the shaft and slip 
the commutator into position. Remove the cotton covering from 
the portions of the loops next to the screws in the segments. 

Insert both wires of one of the loops in the slot in one of the 

screws; this connection should not be in a direct axial line, but 
carried to the second segment beyond, in the direction of rota¬ 
tion. See “F”, Figure 54. Solder the wires in position. 
Bring the second loop to the next segment, and so on until all 
have been connected. The appearance will then be as if the 
commutator had been given one-eighth of a turn after the wires 





HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 











8 


/ 


had been connected. The object of this advance, or “lead”, is 
to bring the brushes in a more convenient position. Shellac the 
connecting wires to prevent unravelling of the insulation. 
Remove the paper from the surface of core so that the ends 
of the sheet iron teeth will be exposed. If the winding has 
been carefully done and tightly pressed in place, no binding 
wires will be needed; but if desired, a place about one-half inch 



motors to cover the exposed ends of the armature with conical 
4 4 dressings” of canvas. The amateur may not feel inclined to 
bother with this. 






























S3 


DYNAMO-ELECTRIC MACHINERY. 


Other windings may be :—Seven volts, suitable for plating, can 
be obtained by using No. 13 (seventy-two one-thousandths inch di¬ 
ameter) wire. Two turns will make one layer, and two layers 
put in each slot for each half winding, and loops brought out as 
usual and four turns wound in the next slot. “D” Figure 55 



9 “ (1 &*,$}- 


r(Short)- 




Q 




I a*> 






L 

<i«o 

r 


4 4 •:< 

L, 




*1* 


T 


6 -32 Tap ^ 


T 

8 





J*—b 


Ha.18 Drill. 


mwp_ 



FIGURE 57. 


shows the eight wires, the blackened ones representing the four 
turns of the first half-winding, the light ones showing the wires 
of the last half. This wire will allow an output of thirty am¬ 
peres, and copper brushes of extra thickness should be used. 

Twenty-five volts. This is a suitable potential for a motor using 
batteries for a source of current. Use No. 17 wire (forty-five 





















































HOW TO BUILD A l-T H. P. MOTOR OR DYNAMO. 


s 9 


one-thousandths inch diameter). Put four turns per layer, three layers 
deep for each half-winding. See “C” Figure 55. It may be neces¬ 
sary to use slightly thinner insulation in the slots in order to 

get the wire in, but the potential is so low that there would 
be no danger of “ground” or “short circuit.” In crossing the 

heads, let six wires be on one side of the shaft, and three on 

the other, in regular order. The halves of the winding will 
then balance the inequality. This winding will allow a cur¬ 
rent of eight amperes. 

One hundred and ten volts. It is practicable to wind an arm¬ 
ature for this potential, but special care and considerable patience will 
be required. No. 26 wire (sixteen one-thousandths inch diameter) is 
wanted. Wind six and one-half layers, eight turns per layer for 
each half winding. “A”, Figure 55, shows the arrangement in 
one slot. There will be 52 turns per segment. The current 
capacity will be two amperes. 

Higher voltage should not be attempted in so small a ma¬ 
chine, as the excessive number of turns of wire introduces 
the insulation so many times as to reduce the amount of copper 
below its safe current-carrying capacity. An armature would 
last so short a time as scarcely to repay the builder for his 
trouble. 

Field Winding . In consequence of the round core of the 
field magnet, this winding can be quickly done in a lathe. 
Figure 56 shows a detail of a spool. It consists of three leatheroid or 
fiber discs four inches outside diameter, the two outer ones having 
a hole two and one-sixteenth inches diameter, the inner one 
two and one-eighth inches. A tin or other thin sheet metal 
tube, soldered along its lapped edge, and rolled with a small 
flange at the ends, holds the discs in position. For winding, 







9° 


DYNAMO-ELECTRIC MACHINERY. 


the spool may be slipped on a wooden arbor with check-pieces 
or flanges to keep the discs from spreading by the crowding 
action of the wire. 

Wind four or five layers of paper around the tin tube, duly 
shellacked. The edges of the paper can be pressed under the 
loose disc and lapped onto the others. Put the starting end of 
the wire through the notch, and draw through a considerable 
length depending on the size used. Wind one turn of this end 

length backwards around the spool and coil the rest around the 

arbor. Press the loose disc against this one turn, and wind two 

or three layers in the main part of the spool. By hand, wind 

two or three turns backwards, from the wire on the arbor. 
Put a piece of thin paper on the main coil and wind several 
more layers; give the end wire a few more turns and so on 

until the requisite number is in place. It will be seen that 

the object of the extra disc and the long protruding end at the 
start was to keep the wire leading to the first layer well insu¬ 
lated from the successive ones, and also to leave the inside end 
so that if accidentally broken off, a turn or two can be un¬ 
wound without disturbing the main part of the spool. 

If fine wire is used the ends may finally be led through 

holes drilled near the edges of the discs, but large wires can 
be tied to the discs by string taken through a number of small 
holes. Leave the ends protruding about six inches. As usual 
with electrical apparatus, shellac the outside layer. 

About fifteen hundred ampere turns are required for field 
excitation; the particular sizes of wire will depend on the vol¬ 
tage of the armature. 

Fifty volts. Series: five pounds of No. 13 wire (seventy- 
two one-thousandths inch diameter) wound eleven layers deep. 


HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


9 1 


Shunt: three pounds of No. 25 wire (eighteen one-thousandths 
inch diameter) wind thirty-three layers deep. For a compound 
field use first two and one-fourth pounds of No. 26 wire 
(sixteen one-thousandths inch in diameter) twenty-nine layers 
deep; wrap on a few turns of thin paper, shellac discs of 
paper over the leading ends of the wires to protect their insula¬ 
tion, and wind, in the same direction, one and one-half 
pounds of No. 14 wire (sixty-four one-thousandths- inch in 
diameter) three layers deep. 

Seven volts. A series field is unsuitable for plating. For shunt 
use four and one-half pounds of No. 17 wire (forty-five one 

thousandths inch in diameter) seventeen layers deep. A com¬ 
pound winding may have in the shunt, three pounds of No. 18 
wire (four one-hundredths inch in diameter) fifteen layers 
deep, and in the series one and one-half pounds of No. 6 wire 
(one hundred and sixty-two one-thousandths inch in diameter) 
one layer deep. 

Twenty-five volts. Series: four and one-half pounds of No. 
10 wire (one hundred and two one-thousandths inch in diameter) 
seven layers deep. Shunt: three pounds of No. 22 wire 

(twenty-five one-thousandths inch in diameter) twenty-three layers 
deep. Probably the builder would have no occasion for a 

compound field for this potential. 

One hundred and ten volts. Series : four and one-half pounds of 
No. 17 wire (forty-five one-thousandths inch diameter) seventeen layers 
deep. It will be noticed that this is identical with the shunt 
requirements for seven volts. Shunt: three pounds of No. 27 

wire (fourteen one-thousandths inch in diameter) forty-one layers 
deep. 

In each case an odd number of layers has been stated in order 








92 


DYNAMO-ELECTRIC MACHINERY. 


to bring the terminals of the coils at opposite ends of the spool. 
Connections . Any kind of seasoned hard wood is suit- 



and drill as shown in Figure 57. Rectangular brass strips are 













































































































































































































































































































































































HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


93 


to oe drilled and tapped 8-32 and attached to the board by 
screws “ f ” (Figure 47), inserted through from the back and 
entering the center holes. The two end screws for each 
strip “g” (Figure 47) enter the board one-eighth of an inch 
to prevent “ skewing.” These holes may be made with a No. 
iS drill, after their location has been marked from the strips. Use 
no shellac on the surface of the brass as electrical contact 
would thereby be destroyed. Connections are made by soldering 
sheet copper clips to the wires and clamping them to the blocks. 
Incandescent lamp cord is suitable for flexible cables to connect 
the brushes with the terminals. One strand will be sufficient 
for the current of a fifty or one hundred and ten volt armature, 
but two strands for the twenty-five volt, and four for the seven 
volt winding should be used, all soldered into a sufficiently large clip. 

By means of this simple arrangement of contact blocks, 
almost any combination of wires may be made, allowing the 
machine to be used for a variety of purposes. Figure 58 also 
shows the necessary wiring for connecting as series, shunt, or 
compound dynamo; series, shunt, or reversing motor. It is not 
the purpose of this book to describe switch-board appliances, 
so locations only of rheostats and reversing switch are shown. 

After assembling the machine, the field wires should be 
straightened, and short pieces of small soft rubber tubing slipped 
on, so as to insure insulation from the frame. 

Testing and Using. The various uses to which the 
machine is put, and conditions under which it works, will de¬ 
termine just which of the connection board arrangements to 
adopt. 

If used as a dynamo to run incandescent lamps or a 
plating bath,—the potential controlled by a rheostat in the field,— 






94 


DYNAMO-ELECTRIC MACHINERY. 


use the “Shunt Dynamo” board, or if fairly close automatic 
regulation is desired, use the “compound” connections. A 
rheostat in the shunt circuit will still be useful to compensate 
for variations in speed. When no rheostat is wanted, connect 

its two points on the board with a short wire. 

In starting a shunt or compound dynamo, turn the rheostat 
until all the resistance is “ out,” that is equivalent to dispensing 
with its use. Let the main switch controlling the lamp circuit 
be “ open.” Drive the armature at its correct speed, 2600 
revolutions per minute. Set the brushes on the “ neutral ** 

point,—that is, on segments which connect with coils just half 
way between the two pole pieces. The correct location is 
shown in Fig. 44. Let the brushes bear with a firm yet even 
pressure; lift one of them from the commutator and touch 
wires leading from a battery, or other source of continuous cur¬ 
rent, to the field terminals. This is to put some initial magne¬ 
tism into the iron. Remove the battery wires and replace the 
brush. Move the yoke slowly back and forth; if current is 

being generated, sparks will appear at the brushes, and strong 
magnetism be felt at the poles. For use, keep the brushes on 

the neutral point, which is the position of least sparking, in¬ 
deed there may be an entire absence of that evil. If no cur¬ 
rent is generated, remove the screws holding the cable termi¬ 
nals and exchange their location by connecting the long one 
where the short one was. The dynamo should now generate. 
Always allow a few minutes for the machine to “build up,” so 
called. A shunt dynamo is often very sluggish in starting. Now 
connect the lamps hy closing the main switch, turning the rheo¬ 
stat if necessary to adjust the potential. Safety fuses of stand¬ 
ard make should be used as shown. In case of overload, or 








HOW TO BUILD A 1-4 H. P. MOTOR OR DYNAMO. 


95 





I accidental short-circuit, the fuses melt and save the armature 
from “ burn out.” 

For starting a compound dynamo,—the same method may 
be used, with the additional precaution to observe that the cur¬ 
rent in the series coil must be in the same direction as in the 
shunt; otherwise its influence would be to oppose instead of 
help the regulation. 

A series dynamo is suitable for running an arc lamp,—in 
this case a small one,—and for general experimenting. Adjust the 
brushes and connect a battery to the line terminals. The arma¬ 
ture will try to run as a motor; if it tries to turn against its 
brushes, remove the battery wires, connect the line, and drive 

the armature in the direction of its brushes; the dynamo should 
now generate. If, when the battery is connected, the arma¬ 
ture turns with the brushes (in the direction in which they 
point), reverse the cables leading from the brush holders. 

Driven in its proper direction again, the armature should gen¬ 
erate. 

Three cases as a motor need to be considered. If uni¬ 
form speed is desired, independent of the load, a shunt field 
should be used. If current is supplied from a constant poten¬ 

tial circuit, a rheostat must be connected in the armature cir¬ 
cuit to prevent an over-current. Turning the main switch will 
allow the fields to get magnetised, but the armature current has 
to travel through the rheostat. As the speed increases, turn the 

resistance out. If the armature tries to run in the wrong direc¬ 
tion, reverse the brush holder cables. If primary batteries are 
the source of current, the gradual lowering of the zincs into the 
acid will obviate the necessity of a starting rheostat. 

For variable speeds a series motor is required; a rheostat 












9<5 


DYNAMO-ELECTRIC MACHINERY. 


will still be necessary for use on constant potential mains. A 

series motor will always run at a constant speed if the load is 
constant; hence it is common to put series windings on fan 
motors because of cheapness. If used to drive a fan a collar 
should be put on the pulley end of the shaft to run against 

the lining and receive the “ end thrust,” the regular shoulders 

being insufficient for so much pressure. 

Besides the ability to run at various speeds, a “reversible” 
motor is sometimes desired. One line wire (Fig. 58) leads to 
the connection board, the other to the reversing switch, which 
is shown in diagram. The circuits are such that the fields 

are always magnetised with the same polarity, but the direction 
of the current through the armature is reversible by moving the 
two parallel fingers of the switch. The reversal of a motor is 
accomplished by changing the current through either field or 
armature,—not through both. A starting rheostat is also in¬ 
cluded in circuit; one of the fuses is omitted in order to make 
the connections more convenient. 

Regular sizes of fuses should be,—for the one hundred and 
ten volt winding, three amperes; this is the smallest size made. 
For fifty volts, four amperes; for twenty-five volts, eight am¬ 
peres ; and for seven volts, thirty amperes capacity. 

If the builder has followed the directions carefully the 
machine will work to perfection,—it cannot help it. This dy¬ 
namo is suitable for a variety of practical uses, not the least of 

which may be as “exciter” for the fields of a small alternator. 
As a motor, it will run a fan, several sewing machines, or 
small lathe. With success assured from the small outlay thus 
required the builder may properly attempt the construction of 
larger machines. 



HOW TO BUILD A TWO-LIGHT DYNAMO. 


97 


CHAPTER IX. 


HOW TO BUILD A TWO-LIGHT DYNAMO. 


N the following pages are given complete directions for 



making a small dynamo and motor for experimental and 
laboratory use; a machine that is not a toy, but capable of 
affording continual interest and profitable research, and will be 
prized by any one of mechanical inclination. 

So many and curious are the applications of electricity that 
to realize their utility and significance, even faintly, is possible 
only by personal experiment and repetition. A set of chemical 
batteries can be called upon to supply a current of electricity, 
but such paraphernalia is inconvenient and expensive. Besides, 
the modern, and only practical method of generating the current, 
is by dynamos. 

Motors, much like dynamos in construction,, run our work¬ 
shops and railways. The young candidate for electrical qualifi¬ 
cations may consider that he has passed excellent preliminary 
examinations if he constructs and owns a practical dynamo. 

Figures 59 and 60 in this article show a dynamo (or 
motor) of simplest design, but a marvel of adaptability. The 
frame, comprising the field magnets and supports for the arma¬ 
ture bearings, is in but two pieces. The armature is made of 
one piece of iron, with one coil of wire. Yet this small 


7 



9 S 


DYNAMO-ELECTRIC MACHINERY. 


machine will require one-man power to drive it to its full capa¬ 
city, and will make a very energetic motor. It will generate 
a current, whether turned in one direction or the other. As a 
motor it can be made to run at will in either direction. Furth¬ 




ermore, it is capable of doing what seems impossible—it can 
furnish a current in a continuous or alternating direction. No 
laboratory or electrical cabinet is complete without some means 
of getting an alternating current. For a continuous current the 











































































































































































































































































































































































HOW TO BUILD A TWO-LIGHT DYNAMO. 


99 


brushes rest on the commutator, as shown in the cut. In this 
case it is self-exciting; that is, the dynamo is complete in itself 

and magnetizes its own fields. By running one brush on each 

of the rings, shown on each side of the commutator, and 
“separately exciting” the fields from some other source, an alter¬ 
nating current is available. By another arrangement of internal 
connections the commutator and collector can be capable of 
making a “self-exciting, alternating current dynamo.” Such a 

combination is not attempted by any machine now on the 

market. 

By winding proper sizes of wire on the armature and field 
cores, any strength, or “potential,” of current can be obtained. 
For ordinary uses a current of 25 volts will be found conven¬ 
ient. No. 18 wire on the armature, and No. 14 on the fields 
would do this. 

At this potential eight amperes could be secured. A higher 
potential, but less current would result from use of fine wire, 
or a lower potential and more current with larger wire. 

The working drawings with dimensions show the construc¬ 
tion so clearly that a detailed description is almost superfluous. 
Making the patterns is tedious, and perhaps inconvenient, and 
with foundries distant, it may be impossible for each one work¬ 
ing independently to avail himself of this article. By clubbing 
together, only one set of patterns would be needed, and cast¬ 
ings obtained at low rates. 

The upper and lower parts a and b of the frame, the 
caps for the bearings and the pulley, are of common cast-iron; 
the armature of annealed cast-iron. The rest of the metal parts 
except the shaft, are of brass. 

In making this machine, the four legs are first to be filed 




lOO 


DYNAMO-ELECTRIC machinery 



FIGURE 















































































































































HOW TO BUILD A TWO-LIGHT DYNAMO 



FIGURE 


6 2 


























































102 


DYNAMO-ELECTRIC MACHINERY. 




FIGURE 64. 




































































HOW TO BUILD A TWO-LIGHT DYNAMO. 


103 


or planed flat, to secure a firm rest on the planer. For the 
next step, plane the parts where the halves of the fields bolt to¬ 
gether, and where caps screw on. The holes may then be 
drilled, tapped, and screws inserted. After the caps c and d 
are tightly screwed in place, the builder may proceed to bore 
out the | inch holes where the bearings of the armature shaft are 
to rest. This can best be done with a boring bar in a lathe. 





figure 65 . 

Or these may be drilled between lathe centers, if the holes are 
afterwards reamed together to insure exactness. I he outside 
and inside rims should be faced smooth that the linings may fit 
nicely. 

To bore out the fields is usually troublesome; but in this 
machine the boring is easily accomplished. After the aims ate 







































DYNAMO-ELECTRIC MACHINERY. 


JO4 

finished, as first directed, a boring bar f inch in diameter, with a 
cutter head in the center can be laid in place, using the arms 
as supports. The boring to size can then be done in any 
screw cutting lathe. 



Hard brass or gun metal is suitable for the bearings or lin¬ 
ing e and f. These are to be made in one piece each, in¬ 
stead of in halves. They are thus easily made, and cheaply 
replaced when worn out. The oil cups g enter the small hole 
in the top and prevent the linings from turning. 

The armature casting h should be annealed by heating to a 
bright red, and then cooled slowly for several hours. Drill the 
rs inch hole through the center and drive it upon a short arbor 
for turning. The outside diameter is to be just 2 inches. As the 
field boie is 2yig- inches, there will be, when the armature is in place, 
uV inch cleaiance. Turn the shaft 1 to its specified dimensions 









































HOW TO BUILD A TWO-LIGHT DYNAMO 



FIGURE 67 




























































J06 DYNAMO-ELECTRIC MACHINERY. 

and drive the armature tightly on the center portion; a few | inch 
steel pins will insure non-loosening. The pulley k is to be 

fitted to the 5-16 inch end of the shaft and held in place by two 
set-screws butting on flattened spots. 

As it is difficult to work copper, brass can be used for 

the commutator and collector. Boxwood or hard rubber will 
make a good hub. The commutator or center portions m 

should be first made. Fit the tube tightly to the center, and 

put in the small screws; then remove the tube and saw it in 

halves. Groove the wood for the connecting wires and fit on 
the two collector rings n. Again remove the brass tubes and 
solder the connecting wires in place. One wire is to connect 

with the inside ring and one commutator segment; the other 
wire with the outside ring and opposite segment. A small pin 
should be put in the shaft to keep the commutator from slip¬ 
ping. Make the position of the division between the commuta¬ 
tor segments as shown in the figure. 

Fit the yoke o to the inside rim of the short lining and 
tap the hole for the set-screw p. Studs or spindles q for the 
brush holders, enter the ends of the yoke suitably insulated with 
hard rubber washers and bushings r and s. Three pieces only 
are used to form the brush holder,—an outside part /, and in¬ 
side part and the screw v. When the screw is tightened 

the brush w (of leaf copper), and stud g is tightly clamped. 

The brass ears a into which the flexible cables are soldered, 
are opened to the center hole to allow easy removal. 

A maple connection board y surmounts the machine. One 
screw in the center is sufficient to hold it. The brush holder 
cables end at two of the binding posts, the field wires at the 
other two. 


HOW TO BUILD A TWO-LIGHT DYNAMO. 



FIGURE 6 S. 



FIGURE 69. 







































































Th'd, 


DYNAMO-ELECTRIC MACHINERY. 


ioS 


The builder is now ready to wind on the wire. File off 
any roughness on the iron, and insulate with several layers of 
manilla paper well shellacked. The armature is to be wound 



FIGURE 71. FIGURE >] 2 . 



FIGURE 73. 


figure 74. 

































































HOW TO BUILD A TWO-LIGHT DYNAMO. 


IO 9 


like a shuttle until filled, with No. iS double cotton covered 
magnet wire; about ij pounds will be required. The four 
sections of the field will take, in all, eight pounds of No. 



FIGURE 75. 


v /*' 


'6 

Shttt copper 

G&Ji eiiisatfA id 
W 

T 

N? 

1 


FIGURE 76. 






Coun ter&ored 
/<>-*,+ AtZti 


: SCT-fUr 



FIGURE 78. 

14 wire. Each section is to be wound in the opposite direc¬ 
tion from its neighbors, in order to make consequent poles 
around the armature. 







































































I IO 


DYNAMO-ELECTRIC MACHINERY. 


Fig. 79 represents a diagram of the winding. When used 
as an ordinary series machine the line wires enter i and 3, or 
2 and 4, the other two being connected with a short wire. 
The diameter in which the dynamo runs is determined by these 
connections. The same holds true when used as a motor. If 



an alternating current is desired, the line is supplied from I and 
2, while a separate current must be supplied to 3 and 4 to 
magnetize the fields. Only two brushes are to be used, one 
on each collector ring. 


fc'Copper u/iri 

Solder 


, ( 1 




■ ; r 

' 1 * 

1 1 1 

« 1 1 

• l 1 

' * 1 




(TWr- 11 — PP= 

SoUcr SoUe* 

FIGURE So. 






























HOW TO BUILD A TWO-LIGHT DYNAMO. 


Ill 


In case a self-exciting alternating current dynamo is built a 
specially connected commutator-collector and yoke are used. 

Fig. 81 clearly shows the connections. Six brushes are 
necessary. The alternating current generated in the armature 
first passes to one of the commutator segments, then from one 
set of brushes, in a continuous direction through the field wind¬ 
ing back to the other set of brushes. By contact of these 
brushes alternately with one segment, then the other, the cur¬ 
rent is directed alternately again into the outside collector ring, 
through the line wire, back to the other ring, and the circuit 
is completed. 



figure 81. 

Other forms of armatures can be designed for use in these 
fields, a drum, or even a ring armature with many segments in 
the commutator. The field winding may be made shunt, es¬ 
pecially for running incandescent lamps. Even a compound 
field is possible. 

For continued use, this dynamo would be driven from a 
line of shafting; but for experiments of a few minutes’ dura¬ 
tion hand or foot power is admissable. 















I I 2 


DYNAMO-ELECTRIC MACHINERY. 




HO 


FIGURE 82 . 

Fig. 82 represents a simple contrivance for driving by hand. 
A cast-iron frame, light but well ribbed, is secured to a board 
or table a few feet from the dynamo by two thumb screws. 
A wheel 15 inches in diameter, 1^ inche face, driven by a 
handle on one of the spokes, will get up sufficient speed to run 
t 16-candle power incandescent lamps, or to run a small arc 

1 n m 


yoke for Self Exci UvLf (liter na.tor 
JVos. 1 a^ioCL for com. try tor brushes 

l ~ A- " Colle.c^toy " 

FIGURE 83. 





































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


“3 


CHAPTER X. 

HOW TO BUILD A ONE-HALF HORSE POWER DYNAMO OR MOTOR. 

A LL the elements of superiority cannot be found in any one 
machine. Preference for one point of excellence must be 
asserted at the expense of some other. In the machine here 
described, there have been held of decisive importance, light 
weight, compactness, simplicity, and cheapness. As high a 
degree of efficiency is not attainable in small dynamos as in 
those of fifty or one hundred horse power, but when the en¬ 
tire output is below one horse power, the variation of a few 
per cent, in waste is negligible. Low first cost is here regard¬ 
ed as of prime importance, with a working efficiency between 
75 and 85 per cent. 

The well known “Manchester” type of field has been 
selected, together with a Gramme ring armature. In detail of 
mechanical construction some originalities are introduced, with 
the aim of making it a modern machine. Complete, it will 
weigh about So pounds. 

Pigs. 84 and 85 show the end and side elevations of the 
dynamo as equipped with a compound field, and adapted to 
running incandescent lamps. Sufficient dimensions are shown in 
the detailed parts, and such explicit information given as to en- 


8 



✓ 


114 


DYNAMO-ELECTRIC MACHINERY. 



FIGURE 84. 































































































































































































































































HOW TO BUILD A 1-2 H. P. DYNAMO OK MOTOR. 



FIGURE 85. 













































































































































































































DYNAMO-EEECTRIC MACHINERY. 


I I 6 

able a person inexperienced in electrical matters to make a 
successful machine. 

Field Magnet and Frame. Referring to the elevations 
in Fig. 86 and the plan Fig. 87, it will be seen that the lower 
half of the structure comprises one pole-piece, the base, and 
the two standards with their caps. Two wrought iron cores 
occupy the middle position, and the upper pole piece sur¬ 
mounts them. 

Very soft cast iron should be used for the pole pieces. 
Provided with suitable castings, the four spots on the bottom 
should first be planed; then stand the base right side up and 
plane the surfaces on which the cores rest, and tops of the 
standards where the caps bolt on. Plane the joints on upper 
pole piece also. Plane the caps and screw them in place by 
means of ijinches-finch-16 hexagon cap screws. Drill the ^ 
inch holes in the pole pieces for the long bolts that hold the 
field together. Their location should first be accurately marked, 
so as to be in line with each other, and the bolts should fit 
well in order that both halves of the field bore should always 
be concentric with each other. 

Soft wrought iron is to be used for the field cores; what 
is commonly called cold rolled steel is so close to wrought iron 
that it is equally suitable. Drill out the J inch holes, and 
drive an arbor in, and turn each to 2J inches in diameter, and 
4 inches long. Square the ends carefully and see that both 
are as near the same length as it is possible to make them. 

Bolt the lower field to the traveling carriage of a lathe 
and with a suitable bar between centers, bore out the ij inch 
holes in the aims for the bearings. The spaces where the cut 
is taken are short, as the cored oil wells and 


grooves occupy 









































































































































































































































HOW TO BUILI) A 1-2 H. P. DYNAMO OK MOTOR. 



the rest of the space. Assemble the frame, and lay a i£ 
inch boring bar in the holes just finished; suspend the machine 
between lathe centers and bore out the field space to 5^ inches 
in diameter. Feed for the cut may be secured by attaching 


figure 87 . 

one corner of the field to the traveling carriage. Insert an L 
shaped tool through a hole in the boring bar and turn the 
groove in the commutator-end pedestal and cap foi the ^oke 
bearing. Remove from the lathe, drill the holes in the leet 


















































































DYNAMO-ELECTRIC MACHINERY. 


I iS 

and caps. The small holes that lead from the grooves into 
the oil wells may be best attempted with a breast drill. Tap 
the holes in the upper field for the eye bolt and the connec¬ 
tion board. Chip out any irregularities that may be in the re¬ 
cesses into which the spools extend. If the builder wishes he 
may tap out holes in the sides of the pedestals for small pet 
cocks, to drain out the oil when desired. 

Armature , Shaft , and Pulley . See Fig. 88. A 

good quality of machinery steel can be used for the shaft, but 

i inch cold rolled steel will answer. Turn one portion to \ inch 
in diameter as far as the shoulder that is left full size; then 
turn to f inch in diameter as far as shown; cut the threads, 
and fit a hexagon nut; then turn to the other specified dimen¬ 
sions, leaving the § inch portions a trifle large for final fitting 
to the bearings. In cutting the J x -A inch keyways, a mill¬ 
ing cutter is preferable to a planer, as there is not the same 
danger of springing the shaft. 

The spiders, Fig. 89, are of gun metal, or tough brass. 
Chuck, or bolt them to a face plate and bore out the holes in 
the hubs. Drive them on an arbor and turn off the rims and 
the arms to the sizes shown. In taking the chip across the 
latter some care will be needed as the arms are slender; a 
greater thickness would interfere with the winding space. Turn 

their ends so as to measure i T 9 ^- inches from the flanges. Cut 

the keyways exactly opposite spokes, and mount the spiders on 
an arbor back to back, with a key inserted. Cut the 32 slots 
in a milling machine or gear cutter, if possible, but a careful 
mechanic will be able to make a hack-saw answer, after care¬ 
fully marking the locations. 

Plain ring punchings of sheet iron are to be used for the 




HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR 


II 9 





FIGURE 88. 













































































































I 20 


DYNAMO-ELECTRIC MACHINERY. 


armature core; they are to be 4^ inches outside and 3 inches 
inside diameter, should slip easily over the arms of the spider, but 
not be loose. One of the spiders may well be a tight fit on 
the shaft; lay in the key, and force this spider up to the 
shoulder. Stand the shaft in a vertical position and slip on as 
many punchings as the spider will hold. Paper between the 



sheets is not necessary. Bind the punchings to the flange with 
a few turns of fine wire; even then the ends of the arms 
should be below the top sheet. Fill the other spider, bind in 
the same manner, and put it in place on the shaft. Start the 
nut on a few turns. Remove the iron binding wires, and 
draw the spiders together by means of clamps pressing on the 
flanges. Be careful not to let any sheets get between the ends 






















































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


I 21 


of the arms. Two or three trials may be necessary to deter¬ 
mine just the right number of punchings to use, in order that 
the coie may be compact yet allow the arms to butt arrainst 
each other. When the core is so solid that a thin knife blade 
cannot be inserted, screw the nut tightly, and remove the 
clamps. If the sheets are not even on their outside ed^es. 
take a light skimming cut in a lathe. Clamp the armature on 
the platen of a drill press and drill a T 3 F inch hole entirely 
through the core and spiders, in the location shown in Fig. 89. 
Then drill the holes in the spiders a little larger, to J inch 
in diameter, and drive a soft iron pin 3J inches long through 
the core. 

The only special feature of the pulley is the long hub on 
one side that receives the end thrust and acts as an oil deflec¬ 
tor. A set screw should be used, impinging on the key. 

Becii'ings .—Gun metal, cast-iron, or babbitt metal is suitable 
for the bearings. They are plain, straight cylindrical castings 
(Figure 90). Chuck them, drill out the holes and ream to f 
inch diameter. Then on an arbor turn the outside to 1^ inches 
diameter, and square the ends. Mount them on an eccentric 
arbor and gash out the grooves in which the oiling rings run. 
Round oft' the resulting thin edge, file out the oil pocket and 

cut the grooves. Oiling rings may be of iron or brass, but may 
conveniently be cut from a suitable size of brass tube. In use 

these rings are half submerged in the oil that fills the wells, 

and as the shaft revolves they slowly turn, bringing up a con¬ 
stant supply of oil. Plugs of brass rod, turned to the specified 

dimensions, serve to cover the holes in the caps, yet allow 
inspection of the rings and admission of fresh oil. The linings 
are to be kept in place in the pedestals by means of protrud- 





122 


DYNAMO-ELECTRIC MACHINERY 










































































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


123 



FIGURE 91. 



















































































DYNAMO-ELECTRIC MACHINERY. 


I 24 

ing J ,inch steel pins, driven tightly through the caps. Set the 
armature in the center of the field, and allow * inch end 
motion of the shaft before locating the pin holes in the linings. 

Commutator .—This structure—the necessary evil of a con¬ 
tinuous current machine—needs to be carefully made. Copper 
bars drawn wedge shaped for commutator segments are now 
easily procurable. For this dynamo 32 segments are required, 
measuring i-J-J inches long, inch wide, .166 inch thick at 

one edge, and .0S6 inch at the other. Prepare, also, 32 strips 
of mica, i| inches long, ^ inch wide, carefully gauged to - 3 l - 2 
inch thickness. Make a turned iron ring, measuring 2 * inches 
inside diameter, and | inch long; the outside may be of any 
convenient dimension not under 2\ inches. Bevel one edge of 

the hole slightly for a distance of about 1 inch. Set the seg¬ 

ments and their insulations together in a circle and bind them 
.with some twine or wire. Force the ring down over them. If 
the ring goes on too easily, insert a little more mica between 
■ some of the segments; if too tight, remove a little mica. Cut 
out the superfluous mica that protrudes into the interior and 
drive in a slightly tapering ii inch arbor. Place in a lathe and 
turn the ends of the segments to an angle of 45 0 , letting the 

length over all be if inches. Force out the arbor. 

To construct the retaining body of the commutator, use a 

piece of seamless brass tube, threaded at each end. Notch one 
end for engaging with a i inch pin in the shaft. Two cast-iron 
flanges are to be made; one is threaded for screwing on the 
tube, the other is an easy sliding fit. Both are turned out with 
conical faces as shown. Around the middle of the tube wrap a 
strip of paper to a thickness of over 1 inch. Use shellac freely 
and when dry it will be sufficiently hard to be turned in a lathe 


HOW TO BUIIvD A 1-2 H. P. DYNAMO OR MOTOR. 


I2 5 






























































DYNAMO-ELECTRIC MACHINERY. 


I 2 6 

to fit inside the segments. From very thin sheets of mica cut 
some rings 2 j 3 inches diameter, with i i inch hole. Cut out 
sectors z\ inches wide as shown. By bringing the remaining 
corners together frustrums of cones will be formed. Shellac 
enough of these cones together, taking care to lap joints, until a 
thickness of ^ inch is reached. Two such complete insulations 
are wanted. Slip one of these over the notched end of the tube 
and screw on the flange; slide on the segments, still held in 
the ring; lay on the other insulation, then the other flange, and 
tighten with the nut. Be careful not to get the segments twisted 

or skewed. Force off the ring, mount the commutator on a | 

inch arbor and turn the outside smooth, finishing with fine sand¬ 
paper. Turn a slight portion of the circumference to an angle 
of about 15 0 and prick-punch each segment in the center of 
that space; then, tilting the commutator at the same angle in a 
drill press, drill with No. 30 size ^ inch deep; tap out 6-32 
threads and insert headless screws that are slotted to receive the 
armature wires. The conical spaces at the junction of flange 
and mica may be wound full of fine hemp twine and soaked 
with shellac. This will keep the mica from splitting. 

Brushes , Holders , arid Yoke .—Two kinds of brushes may 
be used, copper and carbon. The former, with its holder, is 
shown in Figure 93. All the parts are brass excepting the shoe 

or clamp-piece, which is more easily bent of sheet copper. In 

the casting for the body part drill a inch hole to fit the 

stud, and file smooth the cored rectangular slot for the brush. 
Tap for the two thumb-screws; finally saw the slot. The brush 
itself is made of thin planished sheet copper about .005 inch 
thick, cut in strips ^ inch wide and 3^ inches long. Build them 
to a thickness of T 3 6 inch, solder together at one end, and file 


HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. I 27 

« 

the other to an angle of 45 degrees to fit the commutator. The 
copper brush holder is shown in place on the machine in Fig¬ 
ures 84 and 85. A suitable carbon brush holder is shown in 
Figure 92. The center is drilled i 7 e inch as before, as it may be 



Chick. 


FIGURE 93 . 


used with the same stud as the copper holder. Drill a row of 
.jig. inch holes in both faces of the hub, about \ inch deep. 
Coil a spring of .05 inch diameter steel or brass wire; it will 
































































































































































DYNAMO-ELECTRIC MACHINERY. 




128 

be seen that the ends are to be bent at right angles to the 
spiral parts, and slipped into such of the holes as may be 
necessary to give sufficient pressure on the carbon. Let the 



brush, when new, be about 1^ inches long, and slide fieely 
but not loosely in the slot. As the holder seldom needs adjust- 



























































































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


I 29 

ment an ordinary machine screw may be used to clamp it on 
the stud. 

The devices which support the brush holders and permit 
their adjustment are called the yoke and studs. These, with the 
necessary insulations, are shown in Figure 94. Use cast-iron for 
the yoke, and any kind of wood for the handle. Bore out the 
semi-circular part to fit the groove that has been turned in the 
commutator end pedestal. Drill | inch holes in the ends and 
file the circular faces flat, so that the studs may be properly 
held; drill a inch hole through the filled-in portion, for the 
L shaped tightening screw. Make the studs of 1 7 ( . inch round 

brass rod, turned to | inch diameter at one end and threaded. 
The washer that serves as a shoulder should be driven on this 
end, soldered, and turned true. Use hard rubber for the washers 
and bushings. In Figure 95 the yoke, studs, and carbon brush 
holder are shown assembled, the yoke being inclined at some 
such angle as will be found necessary when in use. 

Winding .—Data for winding the machine for either of two 
potentials, no volts and 50 volts, will be sufficient. The in¬ 

sulation and other preparations of the core will be identical for 
both. 

Provide a quantity of thin tough paper in strips 4 inches 
wide, some discs 5 inch outside diameter, with inch hole, 

and also a few pieces of thick drawing paper. Shellac may be 
freely used as an adhesive. Stick a 4 inch strip of paper all 
around the outside surface of the core, slit the edges and lap 
them over onto the flanges. Put, also, a layer of paper inside 

the core, lapping onto the flanges, and* discs at each end lap¬ 
ping over to the other paper. See that every portion of the 
metal, excepting the limb of the spiders, is completely covered. 


9 



130 


DYNAMO-ELECTRIC MACHINERY. 


When dry put on a second layer, being careful to bring the 
lapped joints in different places. Add a third and fourth layer, 
or more, until the insulation is ,,\j inch thickness in all. The 



builder may substitute thin muslin for one layer of paper with 
good results. 

Make four troughs of the drawing paper bent in the shape 
shown at “a” in Figure 96. They may be formed of rectan- 




















































































































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


gular pieces cut 3^ inches long and 2| inches wide, the lips 
being turned over on the long edge | inch back. Make, also, 
32 smaller troughs of strips 3! inches long and 1 inch wide. 
Bend them over a slat about \ inch thick, so that 8 of them, 
when shellacked together, may be set inside of “a” and appeal 
as shown at u a and b.” Slip these insulations in between the 



arms of the spider and shellac them in place. One is shown 
in Figure 96. Fit 8 wedge-shaped pieces of soft wood into the 
troughs to keep them rigid. With the point of a knife peel 
around the rim of the spider for the slots that were sawed in 
the flanges, and when located cut through the insulation radially 























132 


DYNAMO-ELECTRIC MACHINERY. 


and drive in pegs of hard fibre. They may project inch or 
i inch, and superfluous parts cut off later. 

For iio volts provide 3 pounds No. 20 wire (.032 inch 
diameter). Cut off a length of about 29 feet, and beginning at 
each end wind it on two slim shuttles, half on each. These 

shuttles may be of maple, about 1 foot long, 1 inch wide 

and £ inch thick, notched at each end deep enough to hold the 
wire. By aid of these the wire may be easily threaded through 
the center of the core without injuring the insulation. 

From one of the shuttles wind five turns onto the core, 
letting the first turn occupy the center of the space between two 
pegs, and the fifth turn touching the pegs. In the trough the 
wires will be disposed so as to form | of a layer. From the 
other shuttle wind five more turns, thus making one complete 

layer on the outside surface of the core; on the inside the first 

layer will receive a final turn and the second four turns. These 
successive stages may be easily followed by reference to the en¬ 
larged view in Figure 96. Shellac these wires thoroughly, and, 
when dry, wind another series of ten turns, five from each 
shuttle. Shellac and wind 10 more turns. The device of wind¬ 
ing with the two shuttles is to allow both ends of the coil to 

be left on the outside layer, where connections may be easily 
made and dangers from short circuits lessened. It may be found 
that 29 feet is not quite the right length for the coil and 

the others may be cut more exactly. 

When the shellac on this coil is dry remove the wed»e 

from section 2, and wind 30 turns as before; then in section 
3, and so on until all the spaces are filled. Wind the wires 
tightly, straightening out the bends, and pressing each coil firmly 
in place. Do not neglect the compactness of the coils in the 


HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


x 33 


troughs, as the entire winding must be so disposed as to keep 
the armature balanced. 

Twist the end of one coil with the beginning of the next, 
so that, electrically, there will be an unbroken circuit. Slip the 
commutator in position. Remove the insulation from the wires 
where they will touch the connection screws. Lead the wires 
that connect coils 4 and 5 to the segment that is opposite the 
spider arm at 1. Solder both wires in the screw slot and let 
the other 31 loops follow in successive order. The appearance 
will then be as if, after connecting the wires straight, the com¬ 
mutator had been turned one-eighth of a revolution. This lead 
is given to the wires simply for the sake of getting the yoke 
and brushes into a more convenient position. 

For 50 volts use 3 pounds No. 17 wire (.045 diameter), 
wound n two layers, seven turns per layer, as shown in Figure 
96. Each coil will require about 14 feet of wire. If there is 
difficulty in getting a slot in the commutator screw large enough 
to hold both the connecting wires, the two may be soldered 
together just back of the commutator, one of them cut short, 
the other flattened so as to enter the slot. Shellac the loops 
to keep the insulation from unraveling. 

Binding wires must be wound on to prevent the armature 
coils from flying off by reason of centrifugal force. Close up 
to the pegs and in the central space wrap a few turns of thin 
paper, held with shellac, and wind 10 or 15 turns of .015 inch 
diameter brass or German silver wire on each of these strips. 
Do this winding in a lathe, very slowly, so as to be close and 
tight; before loosening the tension solder the wires together. Cut 
off the pegs that project above these binding wires. 

Spools, as shown in Figure 97, are necessary for holding the 


1 34 


DYNAMO-ELECTRIC MACHINERY. 



FIGURE 97. 



























HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


J 35 


field coils. They can be made of leatheroid or fibre washers, 
held together by a tin or sheet brass tube. A third thinner 
washer is useful for keeping the starting end of the wire from 
the main part of tne coil. This one has a larger center hole 
than the outside ones and is notched to allow the wire to pass 
under. Mount the spool in a lathe on such an arbor that the 
washers may be supported. Wrap several layers of paper on the 
tube, letting the edges join tightly against the end washers, pass¬ 
ing under the loose one. Draw a considerable length of wire 
through the notch, and wind one turn around the spool in the 
opposite direction from which the lathe runs. Press the loose 
washer against this single turn and wind several layers in the 
main part of the spool; shellac on a layer of thin paper, then 
from the wire on the arbor continue a few turns in the narrow 
space between the two washers; then several more main layers, 
and a few more from the end length, until the requisite amount 
is reached. If the wire is fine the ends may finally be passed 
through small holes near the edge of the washers; or, if large, 
bind the ends by passing twine around them and through several 
small holes. 

About 2000 ampere turns are required on each spool for 
field excitation, in order to generate the stated potentials on open 
armature circuit, when no load is on. As the load is added an 
increase in magnetizing force is required and the following data 
makes necessary allowance for this requirement. The amounts 
stated are for one spool. 


no VOLTS. 

i. Series:—8|- pounds No. 13 (.072 inch diameter) double 
cotton covered wire; 45 turns per layer; 12 layers. 


136 


DYNAMO-ELECTRIC MACHINERY. 


2. Shunt:—4J pounds No. 24 (.02 inch diameter) double 
cotton covered wire; 120 turns per layer; 30 layers. 

3. Compound, (a) Shunt:—5 pounds No. 24 (.02 inch diam¬ 
eter) single cotton covered wire; 150 turns per layer; 28- layers. 

(<$) Series:—2f pounds No. 14 (.064 inch diameter) double 
cotton covered wire; 47 turns per layer; 4 layers. 

50 VOLTS. 

1. Series:—9 pounds No. 10 (.10 inch diameter) double cot¬ 
ton covered wire, 33 turns per layer; 9 layers. 



figure 9S. 

2. Shunt:—S^- pounds No. 20 (.032 inch diameter) single 
cotton covered wire; 104 turns per layer; 28 layers. 

3. Compound, (a) Shunt:—5 pounds No. 21 (.02S inch 

diameter) single cotton covered wire; 117 turns per layer; 22 layers. 

( 3 ) Series:— 2\ pounds No. 13 (.072 inch diameter) single 
cotton covered wire ; 45 turns per layer; 3 layers. 































































































































HOW TO BUILD A I 2 H. P. DYNAMO OR MOTOR. 


'37 


RheoiM 



Shunt Dynamo 





Field 

FMieoiUit 


Compound Dynamo 



FIGURE 99 . 















































































































































































































DYNAMO-ELECTRIC MACHINERY. 





FIGURE IOO. 





























































































































































































HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


*39 


\\ here possible, an even number of layers has been speci¬ 
fied, in order to bring both ends of the wire at the same end 
of the spool, and be close to the connection board on the 
machine. In a compound winding insulate well the ends of the 
shunt coils, or they may short circuit with the series turns that 
are wound on over them. 

Connections .—Allowance is made for using the machine in 
a variety of ways. Aside from the winding, the method of 
arranging the exterior connections depends largely on the par¬ 
ticular use to which the machine is put. A connection board is 
provided beside each field spool, with a set of contact clips that 
may be so varied in location as to make any of the combina¬ 
tions shown in Figures 99 and 100.. Details are given in Figure 
98. Use well dried hard wood for the bases, and after drilling 
soak them in melted paraffin. Make blocks of sheet brass and 
attach them by means of screws in the center holes. Mark the 
locations of the other screw holes on the front, and drill for £ inch 
or more, so that the short screws may enter the base a little and 
keep the blocks from slipping. Use sheet copper for the terminals, 
into which the ends of the fields coils are soldered. Standard fuses 
of 4 amperes for 110 volts and 10 amperes for 50 volts should be 
located as shown, to prevent accident from short circuits or over¬ 
loading. After securing to the pole pieces by means of the 14-20 
screws, drill J inch holes through the wood, as shown, and for a 
short distance into the iron, and drive in wooden pins to keep the 
boards from moving. It is impracticable to use screws in this 
place, as their heads would be directly under the fuses. 

Incandescent lamp cord may be substituted for ordinary cables 
if the latter are not available. Let the insulation enter the cast 
brass terminals a short distance and solder the wires into holes 


140 


DYNAMO-ELECTRIC MACHINERY. 


drilled to fit. The cables may measure 10 inches long between 
centers of terminals, but the builder may vary the length to suit. 

Testing and Using .—It will be well to assemble the field 
magnets and spools, without the armature, and arrange the field 
connections. So connect the wires that the current may circulate 
in both coils in the same direction. Send a current from a 

battery, or other source of continuous current, through the coils, 

and test the pole pieces for magnetism. The whole upper cast¬ 
ing should be magnetized to one polarity, the lower pole to the 

other. 

The builder will have to determine from the nature of the 

work to be done just which set of connections to adopt. Having 

these arranged, the screws which hold the boards in place may 
be withdrawn and the upper pole piece removed, Put the arma¬ 
ture, yoke, and brush holders in position, replace the pole piece 
and attach the connection boards. If to be used as a dynamo, 

equip with copper brushes; if a motor, use carbon brushes. 

On general principles a dynamo or motor will run in one 

direction as well as in the other. The ordinary direction usually 
adopted is such that if the observer were looking at the com¬ 
mutator end of the shaft, the armature will rotate in the direction 
opposite to the hands of a clock. With copper brushes it will 
not be possible to run this machine “clockwise,” unless the 
direction of the “lead” to the commutator connections be reversed. 
With carbon brushes, however, either direction of rotation is 
allowable. 

Before starting see that the wells in the pedestals are filled 
with thin oil, and that nothing interferes with the proper move¬ 
ment of the oil rin<rs. 


HOW TO BUILD A 1-2 H. P. DYNAMO OR MOTOR. 


I 4 I 

If the machine is to be used as a series dynamo send the 
current from a strong battery, such as several cells of the bi¬ 
chromate type, or other source of continuous current, through the 
circuit by connecting with the “line” terminals. If the armature 
tends to turn in the direction in which the brushes point, reverse 
the connections with the spool terminals, so that the current will 
flow through the fields in the opposite direction and magnetize 
the poles with the other polarities. Again connect the battery, 
and if the armature tends to turn against its brushes, everything 
is right for generating. Drive the armature, using a pliable belt, 
at 2600 revolutions per minute. Connect to its circuit and the 
machine should instantly begin work. Adjust the brushes to the 
non-sparking point. 

If a shunt dynamo is desired, the battery current may still be 
used, but in order to send any current around the fields a rheostat, 
or resistance, should be connected in the armature circuit. This 
may conveniently be done by removing one of the cables and in¬ 
serting a suitable resistance, say io to 20 ohms, in its place. Cut 
out all the resistance in the field rheostat, or simply connect its 
terminals with a short wire. So connect the ends of the field coils 
to the brass blocks that, when the current is flowing, the armature 
will tend to turn in the direction of its brushes. Remove the 
battery wires and replace the cable. Drive the armature at 2600 
revolutions per minute. If the machine does not generate at once 
shift the brushes slowly back and forth past the neutral point. If 
it still fails to generate, examine the fields for polarity, to see that 
there has been no mistake in connecting the coils. Separately 
excite the fields and see if the armature will generate. If it will 
not, then the trouble is in the armature itself, and will require ex¬ 
amination for grounds, short circuits, or open circuits. After the 




14 2 


DYNAMO-ELECTRIC MACHINERY. 


machine has been put in working order connect the lamp or 
other circuit and adjust the potential by means of the field rheostat. 

For a compound dynamo divide the tests into two parts. First 
make it generate as a series machine, leaving the shunt terminals 
disconnected ; then remove the series clips and make it generate as 
a shunt dynamo. Reconnect the series coils and the proper work¬ 
ing conditions should result. 

The diagrams for motor connections plainly show the ar¬ 
rangements. Starting rheostats must be used in the armature 
circuit to prevent burning out from overcurrent. If used on a 
iio-volt circuit such a rheostat may well have an initial resist¬ 
ance of 15 ohms. The use of motors on arc light circuits is 
dangerous, and is not often allowed. 

A good lubricant for the commutator is a mixture of vase¬ 
line and graphite; keep a cloth saturated and occasionally rub it 
on the commutator while the armature is running 1 . Do not let 
the brushes spark; if such action shows itself immediately inves¬ 
tigate the cause and remedy it. These causes may be: (1) 
overload; (2) brushes off the neutral point; (3) rough commu¬ 
tator—smooth it with sandpaper on a piece G f wood and rubbed 
on the revolving surface; (4) bad brushes—see that they are 
clean, fit the commutator, and do not touch more than two 
segments at once. 

It is well to bolt the machine to a wooden bed plate that 
can be given several inches of motion by means of a screw. 
Proper tension can then be secured for the belt, and insulation 
from the ground. 


HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


H3 


CHAPTER XI. 

HOW TO BUILD A ONE-IIORSE POWER MOTOR 

OR DYNAMO. 

In presenting this chapter the writer has had a variety of 
considerations in mind which were regarded as of cardinal impor¬ 
tance. Amateurs have limited tool facilities, and in this motor, 
machine work has been reduced to the minimum. The use of 
a planer has been avoided. A lathe can do all the work. A 
milling machine will be found convenient but it is not essential. 

The field casting is in but one piece. Even the arms for 
supporting the bearings are integral with it. The poles are 
salient, and “end on” towards the armature: the lines of mag- 
netic force do not have to bend in order to go through the 
armature core. The field coils are nearly covered by the iron, 
thereby making the wire most useful in producing the magnet¬ 
ism, and the leakage of magnetism is very small. 

No exterior magnetism can be felt, and any additional 
devices for adapting the machine for particular applications can 
be bolted to the machine at will. Mechanical joints being 
absent there is the best of magnetic circuits. Still the field coils 
can be wound in a lathe upon a form and slipped into position. 
Winding 1 the field coils in sections allows the wires to be con- 


x 44 


DYNAMO-ELECTRIC MACHINERY. 




* 

u Min 11 ill _ 


i iifsw' // 3 iiiiii a 

-1 

BO!iS F= W^ 


FIGURE IOI. 













































































































































































HOW TO BUILD A ONE H. P MOTOR OR DYNAMO. 


r 45 



nectecl for a series motor or dynamo, or in series for a shunt 
machine. 

The armature is in the center of gravity of the machine 
and protected from danger or damage from the outside. The 
core is of the ordinary Siemens drum type, thus most easily 
made and wound. The large mass of iron in it and the field 
keeps the commutator free from sparks. The bearings are very 
simple and practically self oiling. 

The motor is of one-horse power capacity, will pump water, 
blow a large organ, run a small machine shop or printing office, 
will drive a 16-foot boat five or six miles per hour. As a 
dynamo it will run one 2000 c. p. or two 1200 c. p. arc lamps, 
or ten 16 c. p. incandescent lamps, or a sizable plating estab¬ 
lishment. 

The motor may be belted direct to shafting, or by screwing 


10 













































I,4 6 DYNAMO-ELECTRIC MACHINERY. 

extra bearings to the frame the speed can be reduced by gear¬ 
ing. ■ 

The construction of the held is plain from the accompany¬ 
ing drawing.—Figure 103. 

No attempt has been made to make this a lightweight cast¬ 
ing. It weighs a little over one hundred pounds. The efficiency 
of a motor and the conditions of non-sparking with a change of 
load demand a very powerful magnetic held. It is false econ¬ 
omy to begrudge iron for this purpose. 

Several ways are possible in making this pattern for the 
held casting. A good method is to part the rectangular frame 
on a line even with the lower surface of the pole pieces. The 
parts for the pole pieces themselves are loose but are to be 
recessed about half an inch into the frame. By this construe-. 
tion of the pattern coring will be avoided, also expense of the 
core-box, and smoother castings are obtained. 

O11 the ends of the arms where the pedestals for the bear¬ 
ings rest, the middle part is cut away, strips on the inner and 
outer edges alone receiving the machine finish. The bottoms of 
the bearings, Figures 104 and 105 are to be treated in the same 
way. A single bolt through each arm holds the bearings in 
place. 

With the castings at hand, the builder may, if he will, 
work on the field first. The holes are to be drilled as shown, 
the four through the legs for bolting to the base board on which 
the machine is finally to stand. The holes through the ends of 
the arms are T \ inch larger than the bolts, to allow room for 
adjustment of the bearings. The tapped hole in the top is 
adapted to receive an eye bolt for convenience in lifting the 
machine. Two tapped holes on the upper front part of the 









FIGURE I O6, 






























































































































































































































































































































































































































I 

Ift 

■' I 






























i 


























HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


147 


frame are for holding the connection board in place. Now put 

the casting in a fairly large lathe and bolt it securely to the 

travelling carriage: it may be well to remove the tool post slide 
from the carriage altogether. With a boring bar between the 

lathe centers, bore out the fields to the dimensions given. 

If the builder has any misgivings about his ability to get 

the armature winding to its specified dimensions, he may bore 
the field one thirty-second or one sixteenth of an inch larger; 

but he must not forget that the greater the air gap between the 

polar faces and the armature core, the less the output of the 

machine. 

The ends of the arms for the bearings are to be bored out 

to the same radius as the fields. Let the final chip be a light 

one with the holding down bolts somewhat relieved, so that the 
arms may not be sprung any out of line. Aside from the 

chipping and filing necessary to remove lumps and burrs, the 
machine work on the fields is now done. 

The cast iron pedestals are shown nearly in full size in Fig¬ 
ures 104 and 105. They are held on an angle iron on the face 

plate of a lathe or in a chuck, and the holes for the brass 

linings bored. Mount them upon arbors and turn off the lower 
surfaces to the same radius as the field was bored. The brass 
lining for the pulley end is to be drilled from the solid, 

mounted upon an arbor and the outside turned to fit tightly in 
the pedestal. A small brass tube through the bottom of the 
poll cavity will prevent the lining from working out of position. 

It will be noticed that the lining for the commutator end 

bearing is made integral with the brush holder yoke. This 
is a unique method of simplifying the mechanical construction. 
In order to insure oil reaching the shaft, whatever be the posi- 




148 


DYNAMO-ELECTRIC MACHINERY. 


tion o£ the yoke, a groove should be cut in the iron around 
the lining as shown in Figure 105. A knurled thumb knot will 
serve to hold the yoke in any assigned position. 

Holes in the bottoms of the pedestals are to be drilled and 
tapped for the bolts that are to secure them in position on the 
arms of the frame of the machine. At the pulley end a inch 
^ inch, 13 hexagon headed bolt is to be used, a 1^ inch, T ?g- inch 
14 at the commutator end. 

By the construction thus explained and adopted, the builder 
will see that the bearings will, of themselves, come- in line and 
exactly in the center of the field bore. To take out the arma¬ 
ture will require the removal of but one bolt—at the pulley end 
when the armature with its pulley and bearing can be drawn 
out lengthwise, leaving the commutator end bearing with yoke 
and brushes undisturbed. 

The armature with the shaft is shown in Figure 106. Cold 
rolled Bessemer steel is suitable for the shaft. Brass retaining 
heads. screwed on the shaft serve to hold the lamination and 
winding in place. Sheet iron is the proper material of which 
to make the core, but it is possible to wind the space full 
between the heads with fine annealed iron wire, soldering it in 
several places to the heads to prevent slipping. The layers of 
sheet iron offer an easy path for the magnetism, while through 
wire there would have to be a jump from layer to layer. 

It will be found well to arrange this part of the work in 
the following order: If stock for the shaft is of ordinary ma¬ 
chine steel, center and turn it to eleven-sixteenths inch its 
entire length. If cold rolled steel is used, the builder can 
center it so exactly with the aid of the back rest of the lathe 
that turning will be unnecessary. From the ends of the shaft 


HOW TO BUILD A ONE H. P. MOTOR OR DYNAAIO. 


r 4 9 


up to the places where the threads are to be cut, reduce the 
diameter to f in. : cut the threads, 27 per inch for § in. further. 

At the bottom of the threads the diameter will be § in. The 

rest of the turning on the shaft should be reserved until the 
core is built up, as, on account of the variations in the thick¬ 
ness of the sheet iron, the shaft may be sprung or slightly 
bent. 

By referring to Figure 103, it will be seen that the width 
of the field is in. The length of the lamination of the 

armature core should be the same. Wrought iron is commonly 
used for armature heads and forms a part of the magnetic cir¬ 

cuit. In this machine the entire core is sheet iron. Brass retain¬ 
ing heads are used, and these are outside the magnetic path. 
The castings for these heads are hollowed out somewhat on the 
’nside, for lightness and economy of machine turning. They are 
to be chucked, turned on the flat side, bored and threaded while 
in the lathe; or they can be drilled, tapped, mounted on a nut 
arbor, and then turned. Three J-in. holes, as shown, are to be 
drilled in each head. These are for engaging with the pins of 
a spanner wrench, when screwing the heads on. Sixteen slots, 
g 3 4 -in. wide and T 5 g-in. deep as shown are to be cut in each. 
These are for holding the winding pegs. This can best be done 
in a milling machine, but the location for each slot can be 
marked off carefully, then cut with a hack saw. 

Sheet iron .014-in. thick is the standard for armature lami¬ 
nation. Stove-pipe iron is good. The tin-coated iron used in 
making preserving cans will answer also. The thin layer of tin 
will not be detrimental. If the builder has difficulty in procur¬ 
ing sheets punched to size, he can buy a sheet of stove-pipe 
iron and cut it into 35"^* squares. Clamp the requited nuinbei 



DYNAMO-ELECTRIC MACHINERY. 


i5° 

between two metal plates and drill a ff-in. hole through the 

whole mass. Mount upon an arbor, (do not use the shaft for 
this purpose), and clamp them together by means of nuts 
threaded upon the arbor itself. Turn to 3 x 1 ^-in. diameter; there 
will be a saving of time in turning if the sheets have their 
corners clipped beforehand. 

Screw one head on the shaft very tightly, and slide on the 
punchings until there is just room only to catch the threads of 
the other head. Screw this to its right position and ascertain if 
the sheets are tightly pressed together; if there is room to get 
a knife in, remove the head and slip on a few more sheets. 

The shaft can now be put on the lathe, and the core carefully 
turned to its final diameter—3 inches. Finish the brass heads on 
the outside and turn the shaft itself to the dimensions shown for 
the commutator, bearings and pulley. Steel shoulder rings are 
to be forced on as shown, in order to receive the end thrust of 
the armature when running:. 

At the pulley the diameter of the shaft is f inch; at the 

bearing T 9 ^- inch; for the shoulder ring if inch; then to the 

head it is f inch. Beside the other head the diameter is | inch 
again, then T 9 g- inch for the commutator, if inch for the shoulder 
ring, and 1 inch at the bearing. The rings are f inch diameter 
and f inch thick. 

No pulley is detailed, but one 3 inches in diameter, with 

if inch face, for if inch belt, will answer for a motor. For 

some purposes, as for driving a boat, for which the motor may 
be used, a pinion if inches pitch diameter, 1 inch face, iS 

teeth, can be keyed on the shaft. The gear into which the 
pinion meshes is to be mounted on the propeller shaft, and a 

bearing can be screwed on to the bottom of the field casting. 


HOW m BUILD A ONE H. P. MOTOR OR DYNAMO 



FIGURE IO 7 . 
































































l 5 2 


DYNAMO-ELECTRIC MACHINERY. 


Belting should be used wherever possible, as any other device 
wears out the bearings faster and makes more noise. If the 
machine is used as a dynamo it will be well to make the pulley 
4 inches in diameter. 

The construction of a commutator, more than any other one 
part of a dynamo, is a Waterloo to amateurs. There is no 
part requiring better work. Its character directly affects the 
sparking element of the machine; it is the only expensive part 
that receives serious wear. It must be very securely made to 
resist the centrifugal force when revolving. The writer has given 
up the attempt to get a cheap and durable commutator in one. 
The remedy was to describe two different commutators, and let 
the builder make that one which suits his tools and inclination. 

The commutator to be first described is the better one. It 
is shown finished in Figure 107. The sectional view represents 
a “sleeve” with flange at back end. This sleeve is bored out 
t 9 3- inch to fit the shaft. A notch, as shown, is to slip over a pin 
set in the shaft, to act as a key for preventing the commutator 
from slipping. The back flange is turned conical at its upper 
inner edge, and corresponds in shape to the “cap” at the other 
end of the sleeve. A nut threaded on the sleeve holds the 
parts together. These conical surfaces grip the segments and 
hold them securely in position. Either of two methods may be 
observed for making the segments, 16 in number. A copper 
casting in the form of a ring may be procured and turned to 
the dimensions shown in Figure 108. It can then be mounted 
upon an arbor and placed on centers in a milling machine. 
With a saw g 1 ^ inch thick, on the mandrel cut the castings longi¬ 
tudinally almost through into 16 parts. Leave about -fa inch of stock 
at the bottom of the cuts. If a milling machine is not available 


HOW TO BUILD A ONE H. P. MOTOK OR DYNAMO. 


153 



FIGURE I08. 



































x 54 


DYNAMO-ELECTRIC MACHINERY. 


mark off the location of the cuts in this manner:—Take a piece 
of drawing paper i|j5 inches wide and long enough to wrap around 
the ring exactly. Lay the strip flat, divide it with a pencil 
into 16 equal parts. Stick this on the ring with shellac, wind 
string around it and wait a day until it is perfectly dry and 
hard. Remove the string and with a hack saw proceed to saw 
exactly on the pencil lines until each of the 16 cuts are almost 
through the ring. The rim around one edge of the ring is to 
allow for connecting with the armature winding. Half-way be¬ 
tween the division slots cut additional slots through the rim down 

O 

to the surface of the ring; the wires are to be soldered in 
these slots. 



figure T09 


Fit mica or vulcanized sheet fibre to the division slots and 
make this insulation conform to the shape of the inside ring. 
Fit conical rings of shellacked paper inch thick to the tapering 
surfaces. Now cut the segments entirely apart and then set them 
up separated each from the other by the insulation. Put the 
flanged sleeve through, slide on the cap, and screw up the nut 
by means of a spanner wrench. The commutator can then be 
laid aside until the armature is wound. 

The other method of preparing the segments is to have them 
cast separately in the first place. Such an unfinished casting is 
shown in Figure 109. A metal pattern, with the angle pretty 












HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


T 55 


exact, should be made. The 16 castings should he filed until 
they will set up tightly into a complete circle. Shellac a small 
piece of drawing paper on both sides of each segment flush 
with the lower edge._ After these are dry, shellac the outside of 
the papers and set the segments up in a circle around an arbor. 
A short piece of steam pipe should have been previously pre¬ 
pared with 32 set screws, two for each segment. This is slipped 



over the whole and squeezed together by means of the screws. 
The arbor in the center compels them to be kept in a circle. 
If any looseness shows itself between the segments, more insu¬ 
lation should be placed between them. Make sure that the seg¬ 
ments are very tightly pressed together. T et the arbor must 
also be held tightly to allow for the lathe work. The central 
portion only of the arbor, where the segments touch, will be 
about ij inches in diameter. Each side of that the diameter 






DYNAMO-ELECTRIC MACHINERY. 


! 5 6 

should be f inch to allow for reaching the segments with the 
turning tool. (See Figure iio.) 

Turn out the conical surfaces as shown in Figure 10S. 

Carefully drive out the i^ inch arbor. Insert the conical paper 
insulations, put in the sleeve cap and screw up the nut. Loosen 
the set screws, remove the piece of pipe. Mount the commutator 
upon a t 9 £- inch arbor and turn the outside smooth. Saw the 
slots for the wire connections. This latter meth'od is the prin¬ 
ciple of construction adopted by manufacturers of standard 
dynamos and motors. 

To make the simple commutator shown in Figure hi, the 
builder must get a block of vulcanized fibre about 2 inches long 
and 2§ inches in diameter. Drill a T 9 g inch hole through the 

center and turn the outside down true. In one end turn a circle 
i^ inches in diameter, only deep enough to serve as a mark. 
Divide this circle into 16 equal parts and prick-punch each. 

Drill lengthwise through the block with a small drill at each of 
these spots, and finish with a drill T 5 g inch in diameter. (It 

will be best to make a steel templet with 16 holes, besides the 
T 9 g inch center hole. Clamp this on the block and drill accord¬ 
ing to the templet. There will then be no chance of the drill 

running out of line). The holes, when finished, should have 
less than inch of stock between them. It will be necessary 
to put a brass or steel rim on each end of the block, as shown, 
in order to ensure the block from cracking. Brass or copper 
rods 2J inches long are to be driven into the holes, letting one 
end come flush with the block. Slot the protruding ends radially 
with a hack saw for the wire connections. Now mount in a 
lathe, finish the ends smooth and turn down, between the rings, 

through the fiber, to 2 inches in diameter. Each rod will then 


HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


x 57 




- 









FIGURE I I I 


a 

r ! I 


I-*-’ 

- . ) 



































































158 


DYNAMO-ELECTRIC MACHINERY. 



present a circular face insulated from all the others and con¬ 
tribute towards making a serviceable commutator. As the com¬ 
mutator wears the segments will seem to get closer to each othei 
until the diameter reduces to ij inches, then as a center line of 
the rods is passed the thickness of insulation will increase. 


When the diameter has worn to 1^ inches probably the brushes 
will spark disastrously. 

The brush holder yoke has already been made, as it is a 
part of the commutator end lining, so the brush holders, brushes, 
studs, and insulations are in order. These parts are shown 
assembled in Figure 112. Each brush holder consists of three 


figure 112. 








































































































HOW TO BUI1.D A ONE H. P. MOTOR OR DYNAMO. jrg 

parts, shown detailed in Figure 113. The body and shoe are 
brass castings, while the thumb-screws are made of brass rod. 
The paits can be bright finished all over or left rough as the 
builder chooses. The brushes themselves are of leaf copper .005 






FIGURE I 13. 


inch thick, laid layer upon layer until a thickness of £ inch is 
reached. Then a thicker sheet, say .015 inch, is laid on top. 
The whole mass is to be soldered together at one end, the other 
beveled, as shown, to fit the commutator. If the commutator 













































































i6o 


DYNAMO-ELECTRIC MACHINERY. 


first described is built, four brushes can be used, two on each 
side. Only two brushes can be used, one on each side, with 
the commutator last described. 



In Figure 113 the studs and insulations are shown. Two 
studs are to be made; § inch hexagon brass rod can be turned 
to the dimensions given, or § inch round rod can be used by 
driving on hexagon washers to serve as shoulders. The washers 



















































































HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. l6l 

should be driven on over the end that is reduced to J inch 
diameter, soldered, and turned off true. The studs are filed flat 
on one side. By means of the thumb-screw the shoe is wedded 
tightly between the brush holder body and the stud, thus holding 
the brush and brush holder in position. More or less pressure 
of the brushes upon the commutator can be obtained by turning 
the stud by means of a fork wrench upon the hexagon shoulder. 
The bushings and washers for insulating the studs are of hard 

rubber. Brass washers should also be inserted between the nuts 
and the rubber. 

For reversible motors, carbon brushes will be necessary. 
These are shown assembled in Figure 114, details are given in 

Figure 113. For each holder a strip of copper inch thick 
is to be bent as shown and a block of soft carbon inserted in 

the jaw. Immerse the carbon and end of strip in a solution of 
blue vitriol, and, with a battery, plate with copper until the 
carbon is covered and well joined to the strip. With a piece 
of emery cloth on a round stick hollow out the carbons, so that 
they will fit the commutator. 

Maple is suitable material for the connection board. If the 
machine is intended as a series motor or dynamo, the arrange¬ 
ment shown in Figure 115 is to be used. Binding posts for 
circuit wires are in the two upper corners. Terminals from the 
brush holder cables enter the other two corners. The current, 
coming in on one side, enters a long brass strip, from which 

it passes to the field coils by wires as shown, back to the other 
strip and out to the rest of the circuit. . On the other end of 
the board there is simply a straight connection from cable to 
binding post. 

For a shunt motor or dynamo the board shown in Figure 


11 



162 


DYNAMO-ELECTRIC MACHINERY. 



10 


W 

Pi 

P 

O 





FIGURE I l6. 

































































































































































































HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


i6 3 

i 16 is to be used. It will be seen that there is a straight* con¬ 
nection through the fuses from cables to binding posts at each 
end. The field wires are connected in series with each other 
and shunted across the terminals. If the machine is used as a 
motor the two binding posts, Nos. i and 3, are to be connected 
by a straight wire; if as a dynamo these binding posts offer 
connections for a rheostat for varying the potential. This is 
usually necessary to compensate for variations in speed and load. 





Two § inch—14—20 fillister head brass screws will serve to 
hold the connection board in place on the field magnet. Flexible 
cables to connect the brush holders with the terminals on the 
board are necessary. 

Incandescent lamp cord will answer if the double strand is 
used on each side of the machine. A single strand will not 

be quite sufficient to carry the current. The length necessary 
and the tips are shown in Figure 117. 

The tips shown are small brass castings, but sheet copper 
^ inch thick can be used. By curling one end of a short 

strip a suitable receptacle for the cable will be given. It is 
well for the insulation to enter the tips for an eighth of an 
inch. This prevents unraveling, also supports the wires of the 
cable so that they are not easily broken. 



























164 


DYNAMO-ELECTRIC MACHINERY. 


Insulate the armature for winding. Wrap around the shaft 
four thicknesses of thin paper and two of cloth, well shellacked. 
Let this extend from close to the heads for about an inch and 
a half along the shaft. Shellac a disc of thin paper over each 
of the brass heads; let the paper be large enough in diameter 
to lap over on to the cylindrical surface of the core; split the 
edges of the paper to make it lie flat. Wrap one layer of paper 
around the core itself, but this strip should be wide enough only 
to cover what was not reached by the overlapping paper discs. 
Put on a second layer that laps over on to the heads. Put 
small discs of paper over the heads to reach this. A layer of 
common white cotton cloth can be shellacked on, still observing 
the principle of breaking the joints. 

Under no circumstances should a joint come on the edge of 
the heads. An outside layer of paper completes the insulation. 
The diameter of the core over insulation should not exceed 3^ 
inches. With a needle feel along the edges of the core until 
the slots in the heads are found. Cut through the insulation 
with the point of a jack-knife blade. Drive into each slot a 
strip of leatheroid or fiber 6 \ inch thick, T 5 6 inch wide, and 
leave them sticking out about 5 inch. 

The insulation and winding of the armature can well be 
carried on by supporting it between lathe centers. A more con¬ 
venient and simple support is shown in Figure 11S. It is made 
of wood and its construction is too plain to need description. 
The ends of the armature shaft rest in the semi-circular notches. 

Everything has now been described except the winding itself. 
The builder must determine what sizes of wire shall be used, 
by the purpose for which the machine is built. If it is to be 
used as a motor on a constant potential, or incandescent lamp 


HOW TO BUILI) A ONE H. P. MOTOR OR DYNAMO. 


I 6 





















166 DYNAMO-ELECTRIC MACHINERY. 

circuit of iio volts, certain sizes of wire should be used. If as 
a series motor on constant current or arc circuit of io amperes, 
other sizes should he used. 

Other conditions will necessitate something still different. 
The method of winding will be the same in all. For purposes 
of description the following has been selected : 

Winding adapted for series motor for io-ampere arc circuits, 
or with battery power for running a boat or lathe and few 
other tools; or as a dynamo for running one full arc lamp or 

io 16-c. p. incandescent lamps. 

This winding will be for 52 volts potential at the brushes. 
A current of T3 amperes can safely be allowed. No. 16 (B & 
S.) gauge double cotton covered wire is to be used. Place the 
armature core in its support and with the spool of wire con¬ 
veniently arranged, bend the end of the wire so as to hook 

around one of the pegs. It may be tied to the peg if need 

be. With one hand carry the wire along the surface, in between 
two pegs at the other end of the core. With the other hand 

turn the core one-half a revolution, so the wire will be laid 

across the end between the two pegs directly opposite. Do not 
pull it tightly against the shaft, but let there be a space of 

about ^ inch. Bend the wire over the edge and back along the 
core to the other head, then with another half turn of the core 

backward return to the starting point. The same space should 

be allowed between the wire and the shaft as on the other end; 
keep on with the wire alongside the first turn until another is 

placed. The space between the wire where it crosses the heads 
and the shaft will be getting less with each successive turn until 

five turns are placed. The last turn should wedge in tightly. 

Pass the next turns on the other side of the shaft. The winder 






HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


will find that he must rotate the core the other way as each 
successive half turn is placed. Let these turns be close to the 


FIGURE I 19. 


first wires but tight against the shaft. There will be room for 
< nlv four turns on this side of the shaft. Do not cut the wiie 

J 

























































168 


DYNAMO-EEECTRIC MACHINERY. 


when the entire space between the pegs is filled but make a 
loop about 3 inches long, twisting it together until the contin¬ 
uation of the wire points straight across the head. Figure 119 
shows the first coil all wound, also where the beginning and 
end is. Lead the wire into the space alongside the first coil. 

To do this, it will of course be necessary to cross the first coil 

diagonally. Be sure to let there be kept a distance of 5 inch 
from the shaft as before, so as to leave room for the following 
turns. Put on the five turns on that side of the shaft, then 
four on the other side and the second coil will be wound. 
Bring out a loop, twist it together as before, and proceed to 
cover the space between the next pegs. Pull the wire tightly 
when possible and always straighten it carefully with the fingers 
as each turn is laid on. The same order is to be observed for 
winding eight coils. There will then be eight loops left out 

for connection with commutator segments. However, there are 

sixteen segments. How are connections for these to be provided 
for? For a ninth coil start a turn of wire directly on top of 
the one wound at the very beginning. Put a complete layer on 
as if there were no winding already there. It will be noticed 
that on that side of the shaft where in the first layer there 
were only four turns, five will appear in the second layer, and 
four in the second on top of the five of the first layer. So 
the winding is balanced. The second layer over the entire sur¬ 
face will make eight more loops for connections. No cut is to 
be made in the wire at any time, until the winding is com¬ 
pleted, when the last and first ends are to be twisted together. 
Thus the armature circuit is one continuous winding, with con- 
nections allowable at 16 different places. Shellac the whole very 
thoroughly. Figure 120 shows the armature at this stage of 


HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 169 

construction. Cut off the extra insulation on the shaft beyond 
the winding and slip the commutator in place. 

If the machine is to be used for general purposes as dy¬ 
namo or motor, and running in either direction, the loops from 
the armature winding should be led straight to the nearest seg¬ 
ments. Scrape the insulation from the wires where they enter 
the slots in the commutator and solder each carefully. Both 
wires comprising a loop are to be soldered to the same segment 



FIGURE 120. 


and the superfluous ends cut off. It will be seen that the end 
of one coil and the beginning of the next is unbroken. 

With the connections made straight like this, the position of 
the brush holders and yoke, when the armature is running, will 
be about horizontal, provided carbon brushes are used. With 
copper brushes the yoke must be tilted to an angle of 45°. It 
will be possible to allow the yoke to be horizontal, simply for 
looks, by giving the connection wires from the armature to the 
commutator a “ lead.” Instead of connecting a given loop with 
the nearest segment, carry it to the second segment to the right 
or left, depending on which direction the machine is to run. 
The other loops follow in order, giving the appearance that the 
commutator had been twisted out of position one-eighth of a turn. 








DYNAMO-ELECTRIC MACHINERY. 


170 

“Binding” wires will be necessary to hold the copper con¬ 
ducting wires in place. Around each end of the core next to 
the protruding pegs and in the middle, wrap two turns of thin 
drawing paper, well shellacked. Mount the armature in a lathe, 
and with the back gears in use wind tightly No. 25 German 
silver or brass wire on over the paper bands. The beginning 
of the wire can be secured to an armature lead wire. After 
one band has been covered make a quick reach to the next 
without cutting the wire. Solder the binding wires very securely 
together. There is no objection to soldering them all the way 
around. Resin should be used as a flux in soldering electrical 
work, as acid is apt to rust the joints. 

The lead wires to the commutator can be covered with a 
conical sleeve of duck, well shellacked. Bind the cloth in 
position by winding strong linen thread around it where it laps 
on to the armature and commutator. 

Clean the shaft from all shellac, slip on the pulley end 
bearing, put on the pulley, drive in the key, and the armature 
awaits the field winding. 

An armature winding has been selected and described best 
fitted for general work. The field can also be made to accom¬ 
modate itself to several conditions. The coils are to be wound 
in sections, slipped on to the pole pieces, and then connected 
in multiple or series according to the particular application. 

The builder has a choice of the size of wire he may use. 
The amount of energy absorbed in the field is a large factor in 
determining the commercial efficiency of the machine. 

To excite the field sufficiently to generate 52 volts requires 
about 5000 ampere turns. This can be accomplished with a total 
of 2200 turns of No. 18 wire, and for a shunt machine allow- 




HOW TO BUII/D A ONE H. P. MOTOR OR DYNAMO. 


171 

ing 2J amperes of current to flow. On each field core are three 
separate coils all connected in series. On the connection boards 
the ends of the six coils are shown by figures; the odd numbers 
indicate the outside ends, while the even numbers refer to the 
inside ends. Figure 116 for the shunt connection board shows 
the coils connected in series with each other. Figure 115 for 
the series board shows them connected in multiple, making the 
total resistance of the field 3 l Q as much as in the other case. 

Figure 121 shows the “form” to be used for winding the 
field coils. It is made of maple and bolted to the face plate 

of a lathe. Wrap two thicknesses of thin brown paper strips 

around the center piece. 

Do not shellac it but begin winding the wire tightly; let 
the end of the wire be held in a hole through one of the side 
blocks. It is well to run the lathe slowly, even to use the 
back gears. A thin maple strip held in one hand is convenient 
to crowd the wire into position. As each layer is put on it 

should be shellacked and one thickness of thin brown paper laid 
on and again shellacked. The paper will make the layers even 
and with the shellac bind the whole so together that it may be 
removed from the form without injury. Hammer the wire to 
keep it from bulging up in the center. With the best of pre¬ 
cautions, however, it will measure more across the middle than 
at the ends. About 23 layers should be put on, with 16 turns 
per layer. 

The bolts which hold the form to the lathe also hold the 
parts of the form together, so it is an easy matter to take off 

the side pieces when a coil is wound. The center block can 
be driven out as the unshellacked paper that was put around it 
in the beginning will allow sufficient slipping. 



172 


DYNAMO-EEECTRIC MACHINERY. 



FIGURE I 21 

































HOW TO BUILD A ONE H. P. MOTOR OR DYNAMO. 


173 

The ends of the coil should be wound w T ith a little thin 
paper and the whole coil bound together by wrapping cotton 
tape all about it. Each coil will w r eigh about pounds. 

A complete coil is shown in Figure 122. Paper should be 
wound on the pole pieces before slipping the coils in place 



The coils can be held in position by a few w r ooden blocks or 
wedges. 

The coils can be painted with vermilion shellac and the 
iron with a mixture of lamp-black and ordinary varnish The 
brass parts may be polished. If the directions have been followed 
the builder will have no trouble in getting the machine to run 
as a motor. If he intends it as a dynamo the fields must have 
























174 


DYNAMO-ELECTRIC MACHINERY. 


some initial magnetism put into them. This can be easily done 
with a few cells of a battery connected to the field coils. 

If the dynamo is series connected, the main binding posts, 

B and C, are to be short circuited by a wire. If the dynamo 

will not generate, after moving the brushes slowly back and 
forth, excite the fields with the battery, so that the poles will 
be reversed. The machine should then generate. 

A shunt dynamo is usually sluggish in starting or “build¬ 
ing up ” as it is called. Connect the two small binding posts 
with a short wire, but have no connections leading from B and 
C. Excite the fields, and coax the machine for a few minutes, 

by shifting the brushes slowly. If unsuccessful, reverse die 
polarity and the machine should generate. Do not let the 
brushes spark. 

It will be found that the proper speed for the machine is 
from 2600 to 2S00 revolutions per minute, depending on the 

quality of iron used and the care in construction. The machine 
can be wound for no volts if desired, by using No. 20 wire 
on the armature four layers deep in all,, and No. 22 on the fields. 

If used as a motor on arc circuits, a suitable centrifugal 

' O 

governor must be used to keep the speed constant. The motor 
should be connected in circuit with double cut out switches, as 
shown in Figure 123. A series field may also be wound of 
No. 9 wire, using 6 coils as before, each having n layers, and 
seven turns per layer. These coils must be connected in series. 
This, size of wire should be used if the motor is run on arc 
circuits, with the centrifugal governor arranged to cut out or in 
the six different coils one at a time. 

As a shunt motor it should be arranged as Figure 124, 
with a starting rheostat in the armature circuit. 


HOW TO BUILD A ONE H. D. MOTOR OR DYNAMO. 


*75 






































































176 


DYNAMO-ELECTRIC MACHINERY. 


If the builder desires to wind the machine for 220 volts 
the commutator should be made with 32 segments instead of 16. 
Extreme care should be used with the insulation for 220 volts. 

An amateur is warned to desist from any attempt to make 
a motor for 500 volts. Aside from the difficulty of getting 
insulation to withstand such a pressure, the expense of the 
necessary fine wire is beyond the resources of beginners. 



HOW TO BUILD A 20-LIGHT DYNAMO. 


•77 


CHAPTER XII. 

HOW TO BUILD A 20-LIGHT DYNAMO. 

T HE subject of our illustration shown in Fig. 125 represents 
a dynamo of familiar construction of the Edison general 
appearance. It is two-horse power capacity, capable of supply¬ 
ing twenty 16 candle power incandescent lamps, or two arc 
lamps of 2000 candle power each. Running as a motor it 
would supply about ij horse power. The parts of a dynamo 
may be divided into three classes:—1st, the purely stationary; 
2d, the revolving; 3d, the “trimmings,” which serve to connect 
the first and second. This chapter as has been noted will consider 
the first class. 

To generate electricity there must be a magnetic “field of 
force” to act on the armature. This magnetism is made to 
appear in two heavy cast-iron “pole pieces” D D; they re¬ 
ceive their magnetism from the wrought iron “ cores” C C, 
over which the spools of wire are to be slipped. The cores 
are joined at their upper ends by the wrought iron block B. 
Unless due precaution is taken the magnetism in the pole 
pieces would wander through the iron base of the machine, in 
stead of confining its attention to the armature; a hollow cast¬ 
ing of brass or zinc separates the pole pieces from the base. 
The base is of cast-iron and carries also the standards tor the 


I/S 


DYNAMO-ELECTRIC MACHINERY. 


shaft bearings. Two long lifting bolts A A, reach entirely 
through the magnets and the “grid” C, and screw into the 
base; unscrewing these and removing the loosened parts the 
armature lies open to the easiest access. 

The cast-iron standards F F are, in shape, hollow circu¬ 
lar columns mounted on rectangular pedestals; in the four cor¬ 
ners of these are the bolts. Of the standards one is further re¬ 
moved from the pole pieces than the other in order to give 
room for the commutator; it also has a groove turned in its 
inner rim to hold the movable arm that carries the brushes. 
The standards are provided with gun metal linings for the 

shaft bearings. A chamber in each end catches the waste oil 

» 

and holes conduct the oil to the interior of the standards where 
it can be drawn off. 

Provided with the castings, and other material how should 
an amateur mechanic put the dynamo together? 

Plane the bottom of the base where it is to touch the floor 
and drill the holes in the four projections; then plane the upper 
surface in the three places where parts are mounted. Screw 

the standards in position, as nearly as can be estimated. Now 

true out the holes in their upper ends, between lathe centers, 

unless a boring hole is convenient. Plane the grid, top and 
bottom, and secure it in position with two dowel pins, and a 
few temporary bolts. Plane the pole pieces, top and bottom, 
and bore the bolt holes through. Adjust them in position on 
the grid so that their center will correspond with the centre 
line of the standards; mark the position for the bolt holes in 
the grid. Now drill through the latter, andj tap out the holes 
in the base; put two dowel pins between each pole piece and 
the grid, so that there may be no skewing. 



0 I .J 4 6 


10 u 






6 


figure 
































































































































* 


































. 











































HOW TO BUILD A 20-LIGHT DYNAMO. 


179 


The cores should be fairly smooth and have the ends square; 
for this purpose the bolt holes had better be drilled first and 
the cores turned on the arbor. The magnetic yoke B need be 
planed on its lower surface only. Drill the holes through this 
and the parts are ready to be - bolted together. Get a 
boring bar that fits in the holes in the standards and bore out 
the pole pieces to the right diameter 5 0 . The boring need 

not be very smooth, only the armature as it revolves should 
have equal clearance everywhere. 

The linings or bearings should be made in halves so as to 
'take up the wear, and allow easy scraping and cleaning. Nip¬ 
ples in the upper halves enter the oil cup holes in the caps to 
prevent the lining from turning: shoulders at the ends prevent 
longitudinal motion. 

When all this has been done the builder is readv, if his 

courage is good, to undertake the armature and commutator. 

Rotathig Parts .—In the armature and commutator the 
builder will find good tests of his mechanical skill. 

The revolving parts of a dynamo consist of shaft, arma¬ 

ture, commutator and pulley, which are shown in figure 126. 

Good machine steel should be used for the shaft A, and it 

must be smooth and straight. To prevent springing, and afford 
ease in putting the armature together, the diameter in the cen¬ 
ter is i-^g inches. This portion is 6 inches long and has 
threads, 16 to the inch, cut half an inch up at each end. Ex¬ 
tending from the threaded portion to the bearing size, the shaft 
is inch, at the bearings § inch, and for the pulley inch. The 
shoulders at the beginning of the bearings serve to keep the 
armature between the pole pieces; about ^ inch end-play will be 
useful to give the armature a little liberty, and allow the 
commutator to wear smoothly. 



DYNAMO-ELECTRIC MACHINERY. 


I So 


Wrought iron boiler plate J inch in thickness, will do for 
the armature heads U B B.” They should be chucked in a lathe 
and turned on one face, the hole drilled and threaded to fit the 
shaft. For turning the other side and getting to right diameter, 
it will be best to screw them on a short stiff arbor. This arbor 
will be necessary for the next operation ; 32 slots ^ inch wide 
and ^ inch deep are to be cut in the rim of the heads. This 
should be done in a milling machine. These slots are to receive 
pegs that keep in position the copper wire with which the armature 
is wound. 

The center “C’ of an armature called the core is not of 
solid iron, as the rapid magnetization and demagnetization would 
heat a solid mass sufficient to burn the insulation of the wire. 
Sheets of the softest iron, about inch thick, separated by 

tissue paper, are used. For this machine the sheets should be 
about 4J inches in diameter with a i t l inch hole in center. 

Screw one of the heads very tightly on the shaft and lay 
on a sheet of paper, then a sheet of iron, another of paper, 
and so on until the right amount is built up. It will require 
a few trials to determine just the number of sheets necessary. 

Screw on the other head as tightly as possible and see 
that the whole length is just right—6 inches—the same as the 
width of the pole pieces. Holes may be drilled in the heads 
to admit the use of spanner wrenches for tightening. A § inch 


bolt covered with paper, except at the threaded portion, inserted 
through a T 7 6 inch drilled hole, must be put in the core, as shown, 
to bind the whole together. With this precaution the sheets 
cannot slip nor the heads unscrew. The armature is now to 
be put in a lathe, and with suitable steady rests to prevent 
springing the shaft, turned smoothly to its correct diameter, 4! 
inches, the heads beveled and corners rounded. 


HOW TO BUILD A 20-LIGHT DYNAMO. 


iSl 


Theie aie seveial ways to make a good commutator, but 
any one of them requires time and care. It is the only part 
of R dynamo that iecei\es serious wear j besides a poorly 7 made 




figure 126 . 

commutator will spark so as to work its own destruction. 

Get a casting of as nearly pure copper as possible and 
turn it to the shape shown in section at H. Mount it on an 
arbor in a milling machine, and saw it with a cutter ^ inch 


















































I§2 


DYNAMO-ELECTRIC MACHINERY. 


thick, almost through, into 32 sections. Intermediate slots y 3 ^ 
inch deep, T \ inch wide, in the flange portion, will make allow¬ 
ance for connecting the wires with which the armature is to be 
wound. Fit mica to each of the dividing cuts and make the 
pieces of the same shape as the commutator segment. Washers 
“JJ” of vulcanized fiber are turned to conform to the shape 
of the brass shell E and copper segments H. The ring K is of 
the same shape as the head of the shell E, and is to be forced up 
by the nut G. With a hack saw separate the segments H 
entirely, and file off the burr from each. These with the 
mica between can be set up to form a cylinder around the 
fiber bushing F. It will be well to make the outside diameter 
of this bushing about ^ inch less than the hole in the copper 
body of the commutator so that when the shell and ring are 
put in place and the nut screwed up, the mica may be tight¬ 
ly pressed between the segments. After the outside has been 
turned and smoothed with fine sandpaper the commutator will 
be ready to put on the shaft. For securing it in position a set 
screw may be used, the blank end of which enters the shaft 
^ of an inch. 

The pulley is of no special construction. An ordinary iron 
one will do, but a paper or wooden face will have its advan¬ 
tages ; 4 inches in diameter and 3 inches face will be sufficient. 
Set screws butting on the shaft are permissible in a small 
machine like this, but it will be better if they rest upon a key. 

Last of all for this stage of the work, the armature should 
be set upon horizontal ways and balanced. This can easilv be 
accomplished by drilling J inch holes through the heads on the 
heavy side. 


HOW TO RUILD A 20-LIGHT DYNAMO. 


183 

Trimmings .—By the trimmings of a dynamo the reader is 
not to understand that these parts are for ornament only. In 
fact they are essential, as they serve to connect the revolving 
with the stationary parts, to connect the dynamo with the cir¬ 
cuit it is intended to opeiate, and to provide means for regulat¬ 
ing the action of the machine. 



Like the main part of the dynamo these accessory parts 
may be any one of a variety of forms. These are shown in 
figures 127 and 128. 

The “brushes” are a very important part of a dynamo; 

































































DYNAMO-ELECTRIC MACHINERY. 


1S4 

they should be very springy, yet bear firmly on the commutator. 
Those shown here at EE, are two of the set of four to be 
used. They consist of a large number of leaf copper ribbons 
laid one on another and soldered at one end. The other end 
is beveled to fit the commutator. Two independent brushes are 
used on each side so that one may be removed and repaired 
or adjusted without stopping the dynamo. 

The brush holders C C are of brass castings. Through one 
end of each a slot ^ xf inch admits the f inch brush; a suit¬ 
able thumb screw and jam plate holds the brush securely in 
position. The opposite end of the holder is sawed through to 
a half inch hole and pinched by a thumb screw M against the 
brass spindle D. Hard rubber washers and bushings clearly 
shown in the figure insulate the spindles from their holder B, 
called the yoke. 

The position of the brushes on the commutator must be 
adjustable; for this purpose the yoke has its center bored out 
to fit the groove turned on the inner rim of one of the bear¬ 
ings d escribed in the first article. To prevent undue movig 
a clamp consisting of a bent rod G tightened by the thumb 
nut F binds against the lower part of the groove. There will 
be sufficient elasticity in the rod to allow the rod to be moved 
when desired without loosening the nut, yet the vibration or 
jarring of the machine will be insufficient to alter the position 
after once being set. 

At L washers are shown to receive the direct action of the 
nuts, but they also serve to attach the flexible cables that con¬ 
duct the current. One side, not shown, should be extended into 
a tang about half an inch wide; this can be curled so as to 
allow the cables to enter and be soldered in. 


HOW TO BUILD A 20-LIGHT DYNAMO. 



The cables lead to the connection board. This switch or 
connection board will vary according to the purpose for which 
the machine is built. Shunt, series or. compound winding of 
the wnes of the dynamo or motor will alter the connections. 
The one shown is lor a shunt dynamo, and is of such construc¬ 
tion as to be readily adapted to other conditions. A maple 




FIGURE I2S. 


board forms the base. As it fits on the commutator side of the 
magnetic yoke of the dynamo, it must be of the same size— 
3x12 inches. The switch in the center consists of a sheet brass 
blade K, £ inch thick ; at each end is a right angled projection that 
enters between the brass contacts M, held in brass blocks E 
and D. The surfaces of each must be scraped or filed to 
make uniform contact. The builder may use his own ingenuity 
in getting the switch blade pivoted. One way is suggested. 
A stud I is held rigidly in the board by a. countersunk nut, 
the blade K attached to the hard rubber handle F, on this. 












































































DYNAMO-ELECTRIC MAC MINER Y. 


I 86 

A pin through F, and through an elongated hole in the stud 
will limit the amount to which the switch may be opened, yet 
keep the blade in the right position to enter the contacts M. 

Contact blocks B, and H are also of brass held on the 

board by screws J as shown. The holes in the back of the 
board should be filled with resin or shellac. Wires for con¬ 
nections are to be held under the washers and nuts. 

The conventional form of binding posts seen on bells and 
telegraph instruments are not suitable for a dynamo. Besides 

offering insufficient surface, thumb screws easily rattle loose. 

Safety fuses are desirable in this machine, and places are pro¬ 
vided for two, one on each side of the circuit. The current 

should pass from one set of brush holders by a flexible cable to 
the clamp 3 on E; through the switch blade to 1 on D, 

through a fuse to 1 on B; thence from 4 to the lamps, or 

whatever the dynamo supplies; back to 4 on C, to 2, through 

a fuse to 2 on H, and by a flexible cable from 3 on H, to 
the brush holders on the opposite side of the commutator. 

No description has yet been given for the field spools. 

These are very simple, consisting of J inch brass flanges or rings 
united by tin cylinders. Allowance should be made for wind¬ 
ing wire 1 inch deep radially. The spools should slip easily over 
the cores and be short enough to allow the magnetic yoke to 
rest evenly on the cores. 

Thus far the builder has done a large amount of work, 
but the whereabouts of the electricity, for which the dynamo is 
intended, remains unseen. 

Let us suppose that the builder wishes to supply 20 incan¬ 
descent lamps. These may be conveniently 75-volt lamps. The 
armature should then be “wound” with No 15 (B. & S. 


HOW TO BUILD A 20-LIGHT DYNAMO. 


187 

gauge) double cotton-covered copper wire; S pounds will be 
sufficient. Insulate the core thoroughly with paper and shellac, 
tV mch thick in a U* Cut through into the slots in the heads and 
drive in the 32 leatheroid pegs in each. To show these on a 
larger scale the armature is represented as having only 8 pegs. 
(See Figure 129). 

The winding can be conveniently done in a lathe. Leave 
an end of 6 or 8 inches at the commutator side and pass the 
wire between any two pegs, then parallel with the shaft, be¬ 



tween corresponding pegs in the other head, across the end, 
back between pegs diametrically opposite to the starting point. 
Continue the wire alongside the first turn until the whole space 
is filled. Six turns will do this. Do not cut the wire, but 
make a loop of 4 or 6 inches and wind the space between the next 
pegs likewise, make a second loop and wind the third space 
and so on until the whole surface of the core is covered with 









FIGURE 1^0. 


















































































































































































































HOW TO BUILI) A ONE H. P. MOTOR OR DYNAMO 


189 



FIGURE 1 31 

































































































DYNAMO-ELECTRIC MACHINERY. 


IQO 

one layer of wire. This will give 16 loops for connecting with 
the commutator. Thirty-two loops, however, are needed. Con¬ 
tinue a second layer on top of the first between the same pegs. 
When this is done join the ends with the beginning and the 
2 loops are ready to be soldered into the slots in the commu¬ 
tator ears. Do not connect these straight, but give them a 
“ lead,” so that when running, the brushes may be in a con¬ 
venient horizontal position. Connect a loop with the fourth 
segment away from the nearest one and let the other loops 
follow in the same order. 

Upon paper strips in four equally distant places wind tight¬ 
ly wrapping wires of fine brass. This will keep the copper 
wire in place. 

Usually a hood of canvas is put over the ends of the ar¬ 
mature to give a neat appearance. 

Insulate the spools like the armature and wind 10 pounds 
of No. 23 wire on each and connect the two spools in series. 

At 2,200 revolutions per minute this machine should give a 
current of So volts and has a capacity of 15 amperes. 

The exact winding of a dynamo depends on such a variety 
of considerations that for a particular case the builder is ad¬ 
vised to consult an electrician, but the winding here indicated 
will be easy, and the machine will supply a current of conven¬ 
ient strength for a large variety of experiments. 


HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


I9I 


CHAPTER XIII. 

HOW TO BUILD A IOOO WATT ALTERNATING CURRENT 

DYNAMO OR MOTOR. 

I N their natural state dynamic currents of electricity are alter¬ 
nating in direction. Continuous currents are procurable from 
dynamos by the use of “commutators,” which “rectify” the 

successive alternations—send them through the exterior circuit in 
one direction. In “alternators” the current is supplied to the 

circuit in the same form as it is generated in the revolving 
armature. 

Alternating current dynamos have the advantage that with 
the same weight of materials about twice the output can be 
secured which is possible with direct current apparatus. Added 
the simplicity and durability of the collector rings, in place of 
the troublesome commutator, and the ability to transform its 
potential to any desired value, and the alternator offers substan¬ 
tial economic features. Its disadvantages consist in its inability 
to excite its own field magnets, and to run ordinary arc lamps 
and motors. 

This chapter describes a “single phase” dynamo, weighing 
about 150 pounds, having an easy output of 1000 watts, but can 
furnish 1500 watts without danger. That is, wound for 50 volts, 
it will furnish 20 to 30 amperes, or light 16 to 24 ordinary 


193 


DYNAMO-ELECTRIC MACHINERY. 


16 c. p. incandescent lamps. It is possible, also, to use the 
machine as a synchronous motor of about 1 horse power capacity, 
but some exterior devices must be employed to revolve the 
armature at full speed before it can assume its load. In either 
case field excitation is to be supplied from a separate continu¬ 
ous current dynamo. 

Assembled views of the machine are given in Figures 133 
and 134. In general the mechanical construction consists of a 
base supporting two pedestals for self-oiling bearings, and, be¬ 
tween them, the field magnets. Besides the main driving pulley 
the shaft is extended at the collector end for carrying a smaller 
pulley to drive an “exciter” for the field magnets. Electrically 
the armature is “toothed,” with the coils wound around the 
projections; the field is laminated with inwardly projecting 
salient poles. 

The detailed construction may be divided as follows:— 

. Base and bearings. 

2. Field magnets. 

3. Armature, shaft and pulleys. 

4. Collector rings. 

5. Brushes, holders and studs. 

6. Winding. 

7. Connections. 

8. Assembling and using. 

Base and Bearings .—Ordinary cast-iron is suitable for these 
parts, as they form no part of the magnetic circuit. Figure 132 
shows the base in detail. It is box-like, with an opening in 
the center to admit the field, and has various raised surfaces, or 
“bosses,” on which the upper structures rest. The machine 
work will consist in planing first the four bottom corners, then 





FIGURE 


HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


193 










































































































































*94 


DYNAMO-ELECTRIC MACHINERY. 


the necessary spots on the upper surface. Drill the T 7 ^- inch 
holes in the corners, which are to admit holding-down bolts. 

The pedestals (Figure 135) may next be machined. Plane 
the bottoms first, then the upper surfaces; plane also the caps, 



FIGURE 133. 

and screw them to the pedestals by means of the i^-f-16 hex¬ 
agon cap screws. In the lower ledges drill the i^-inch holes, 
and clamp the pedestals in their proper places on the base. 
Set the JJ-inch drill through the holes just drilled, and cut into 
the base about J inch. Mark the parts, so that they may be 


























































































































FIGURE I34. 


HOW TO BUILD AN A LTKRNATING CURRENT DYNAMO 


J 95 


























































































































DYNAMO-ELECTRIC MACHINERY. 


I 96 


\ - 




FIGURE I35. 
















































































































































































































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


l 9 7 


returned to the proper locations; remove the pedestals, and run 
a J-inch drill through the depressions, and tap the holes T %-inch- 
iS. Replace the pedestals, and holt them in place with the 
I 'i%"in c h* I S hexagon cap screws. Drill ^-inch holes on opposite 
sides as shown, and extending into the base about J inch. Drive 

in steel pins that may enter the base inch and be filed off 
on the upper end, even with the ledge on the pedestal. These 
are to act as dowels for preserving the alignment of the bearings. 

Bolt the structure, as it now stands, to the travelling-carriage 
of a lathe, and bore out the holes in the pedestals to if-inch 

diameter. The castings should be so made as to require cutting in 
two narrow belts only. Drill the ff-inch and the f-inch holes 
in the caps for the bearings, and the J-inch slanting holes that 

lead from the grooves to the oil-well. Holes may also be drilled 
and tapped for inserting small pet-cocks for drawing off the oil 
when necessary. The oil-wells must be thoroughly cleaned from 
scale and sand that would otherwise cut the bearings. After 

o 

scraping as thoroughly as possible, it would be well to let the 
cavities remain filled with water for a week or two, that the 
rust may remove the remaining grit. 

Linings, or bushings (Figure 136) for the bearings may be 
either of babbitt or gun metal. Drill out the center holes and 
ream them to f inch diameter. Turn the outsides to if inch on an 
eccentric arbor, gash out the central slots for the oil-rings; round 
out the internal corners and cut the grooves. Oiling-rings may 
be made of castings or cut from a suitable size of brass tubes. 
Bevel the edges as shown * Plugs for filling the holes in the 
caps may be' made from brass rod. 

Field Magnets. For holding the laminations (Figure 137) 
of the field together cast iron rings or flanges are to be used. 





FIGURE 136. 


































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


1 99 


See Figure 138. If cast flat, the surfaces which press against the 
sheets will not require planing. In one flange, drill and counter¬ 
sink ii-inch holes as shown, also drill and tap the six holes 
for the connection board's; the other flange requires nothing at 
this stage. If punchings of sheet iron cannot be obtained, as 



shown in Figure 137 , sheets 11J inches outside diameter, with 6 
inch holes may be procured, and clamped between the two 
flano-es. Use a sufficient number of sheets to make a compact 

O 

laminated mass three inches thick. Continue the ^-inch drill 
in two of the holes in the flange, through the sheets; as soon 
as the other flange is reached, finish with J-inch drill and tap 







































200 


DYNAMO-ELECTRIC MACHINERY 



* 


FIGURE 138 
























































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 201 

the holes y% inch iS. Insert bolts in these holes, remove some 
of the clamps and drill two more holes and insert other screws, 
and so on until the whole eight are in place. Mark off care¬ 
fully the location of the eight holes. Drill several f-inch holes 
through the sheets tangent to the narrowest portions of the 
flanges; insert a hack-saw blade and saw to the line of the 
pole pieces; then from the 6-inch center hole saw along- the 

<T> 

sides of the hole, leaving if inches wide. File off the burrs 
and round the corners. Set the field thus formed into the base, 
and adjust its position centrally by calipering from a temporary 
shaft laid in the bearings. The requisite amount to plane from 
the four lugs can then be determined. Clamp the field in its 
correct location, and drill f-inch holes through the lugs and into 
the base for a short distance. Remove the field, continue drill¬ 
ing T Vinch diameter and tap f-inch 16. Replace and bolt the 
field, to the base by means of the if inch f-inch 16 hexagon cap 
screws. Lay a boring bar in the bearings and finish out the 
diameter of the fields to 6^, inches. It will be necessary to 

clamp the sheets together at the ends of the poles, or the bor¬ 
ing cutter will tear or bend the sheets. 

Armature Shaft and Pulleys. Procure a suitable length of 
if-inch diameter cold-rolled steel, and turn it, excepting the qf- 
central space, to if inch diameter. (See Figure 139.) On the 
ends of this space cut threads, 16 per inch, for a distance of 
f inch. It is well to cut the key way at this stage, in order 
that the slight springing caused by the planer tool may be eli¬ 
minated by the subsequent lathe work. Let the key way be fxf 

inch and begun with the threads at one end and extend .into 
the 1 f-inch portion about f inch at the other. Turn the re¬ 
mainder of the shaft to the specified dimensions, fitting the f- 


202 


DYNAMO-ELECTRIC MACHINERY 



FIQURE I39. 


















































































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


2 °3 


inch diameters to the bearings. Sink a - J-inch pin in the loca¬ 
tion shown for holding the collector. Two cast iron heads are 
to be screwed on the threaded portions of the shaft, the la¬ 
minated core of the armature being clamped between them. A 
detail is shown in Figure 138. First, thread the castings to tit 
the shaft, and surface off the spots which are to press against 
the sheets. It will be noticed that the outer rim is not contin¬ 
uous, being gashed in eight places with crescent-shaped open¬ 
ings. Their purpose, along with the eight drilled and counter¬ 
sunk holes, will be explained in connection with the armature 
winding. Cut Jx^-inch keyways across the threads. Screw one 
of these heads, or flanges on the shaft next to the collector 
end; match the keyways, and press in a ^-inch square key, 4^ 
inches long, as far as the end of the keyway in the i^-inch 
portion of the shaft. 

If sheet iron for the armature core, as shown in Figure 137, 
cannot be procured, provide puncliings 6 inches in diameter, 
with ij-inch hole, and JxJ-inch key way, Clamp a sufficient 
number to make 3 inches in thickness on a suitably keyed 
arbor, and mill or saw the eight slots. Slip the sheets on the 
shaft, with the slots in the same location as when milled; lay 
a tightly fitting bar in one of the slots to keep the end punch- 
ings from turning, and screw on the other head tightly; match 
the keyways, and drive the key back until its ends are flush 

with the hubs of the castings. 

Put the core and shaft thus made, in a lathe and take a 
skimming cut across the sheets to remove the slight inequalities 
in the surface. 

The pulleys are, as usual, of cast iron, but should be 
turned on the inside of the rims also, so as to be balanced. 


204 


DYNAMO-ELECTRIC MACHINERY. 


J-inch square key is needed for the main driving pulley, held in 
with a 5-inch set-screw; but a round pin and T 3 F -inch screw 
will suffice for the exciter pulley. 



Collector. This consists of two copper rings mounted on a 
wooden hub. Each ring represents a terminal of the armature 
winding. If seamless copper tubing cannot be procured, castings 
of gun metal may be substituted. Turn the lings smoothly and 
tap a hole with 14—20 threads in each. 

















































































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


20 ; 


Box-wood, lignum-vitae or thoroughly seasoned maple will 
answer for the hub; but after turning and drilling it to the 
requisite dimensions, let it soak in melted paraffin for a few 
hours. Make two copper connectors, having the center por¬ 
tions threaded 14—20, one end turned to ^ inch diameter, the 
other flattened and tapped 10—24. Press the rings on the hub, 
letting the tapped holes come over the f-inch holes drilled in 
the wood. Insert the connectors from the inside; the small ends 
will drop through the rings, and may be gripped with a hand- 
vice ; screw the connectors tightly. Into them screw the long 

and short brass rods as shown, Figure 140. Solder-sweat the con¬ 
nectors into the rings. 

Brushes , Holders and Studs. Copper brushes are commonly 
used on alternators; the continuity of the rings and the absence 
of sparking renders carbon brushes unnecessary. A brush and 
its holder is shown in Figure 141. Make the brush of thin leaf 
copper, cut in strips 3^ inches long, ^ inch wide, and built to 
a thickness of ^ inch. Solder the sheets together at one end, 
and bevel the other to an angle of 45°. The holder is a brass 
casting, having a round hole to fit the stud, and a rectangular 
opening for the brush. In machining, do not saw the slot 

until after drilling and tapping. Thumb-screws are to be made 
from brass rod, and the presser shoe of sheet copper. 

Two brass studs are required for supporting the brush 

holders. These, with their insulations, are shown in Figure 142. 

One is necessarily longer than the other. They may be made 
from brass rods or castings. Hard rubber is best for the washers 
and bushings. On reference to Figure 135 it will be seen that 
the cap on the smaller bearing has two lugs projecting from 
one end. These are to be drilled § inch, and the surfaces faced 
true, and the studs attached. 


206 


DYNAMO-ELECTRIC MACHINERY. 


Winding. As the machine is likely to be used either as a 
dynamo for supplying incandescent lamps, or as a motor on 
alternating currents, only one potential need be described, i. e., for 



50 volts. For held excitation, however, it may be well to state 
several sizes in order that some dynamo already in the builder’s 
possession may be utilized. 

Eight held coils are required. They may conveniently be 
wound in the form shown in Figure 143. This is made of three 



























































































































































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 207 

separate pieces of hard wood. Clamp the form to the face plate 
of a lathe by means of screws through the two ^ inch holes. 
Wind a strip of thin paper if inches wide two layers deep 
around the neck of the form, but do not shellac it to the wood. 
Start the wire through the small hole, and wind one layer. 
Shellac it, and wrap on one thickness of thin paper; wind on 
a second layer of wire and stick on a second strip of paper, 
and so on until the form is full. As each layer is put on 



hammer it flat, and see there are no gaps between the convo¬ 
lutions. When the shellac has dried on the outside layer, remove 
the bolts and separate the sides of the form from the coil; by 
running a thin case knife around close to the wood, the wire 
may be kept from getting deranged. Remove the center block. 
As the shellac on the interior layers will still be undried, lay 
the coil between two sheets of paper and put it under a few 



























































































2 o8 


DYNAMO-ELECTRIC MACHINERY. 




pounds weight. In a few days, when thoroughly dry, tear off 
the superfluous paper, and, leaving the terminal wires on oppo* 
site sides, cover the coil with cotton tape. Immerse it in shellac 
for a few moments, and then when dried it is ready to be slipped 
on the pole piece. Care should be exercised to get the same 
number of turns in each of the eight coil in order that the field 
magnets may be uniformly magnetized. 



figure 143. 


d he field winding should be, with an exciter giving 25 volts : 
No. 16 single cotton covered wire, each coil having 25 turns per 
layer and io layers. Total weight, 15 pounds. 

Fifty volts: No. 19 single cotton covered wire, each coil 
having 34 turns per layer and 13 layers. Total weight 13 pounds. 

One hundred and ten volts: No. 23 double cotton covered 
wire, each coil having 40 turns per layer and 16 layers. 














































HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 


209 


Total weight 8 pounds. The 25 volt winding is preferable as the 
larger wire introduces a smaller proportionate amount of insula¬ 
tion, and allows a higher number of ampere turns than in the 
other cases, and the strength of the field largely determines the output 
of the dynamo. A de\ice foi holding the coils on the pole pieces is 
shown in Figure 145. Drill and tap a hole 8-32, 1 inch deep on both 
sides of each pole, about J inch distant from the cast-iron 
flange. Procure 16 strips of soft sheet brass 2 inch lone, A 

inch wide and y 1 6 inch thick. In one end drill 4^ inch holes, 
and attach the strips to the poles with J-S-32 iron round head 
screws. Slip the coils on the poles, drive tapering wooden 
wedges into the spaces at the ends of the coils, which will 
both serve to keep the coils from moving and to press the 

sheets of iron together. Now bend the brass strips over the 
wedges tightly against the coils. Between the coils and strips 
press bits of shellacked pasteboard or leatheroid to act as extra 
insulation. 

Any potential, other then fifty volts, can be secured from 

the armature winding by using a proportionate number of turns 
of wire. To prepare the core, round the corners and shellac 
a layer of thin cotton cloth over every part of the sheet iron, 
and extending over on the cast iron heads for about £ inch. 
When dry, put on a layer of thin tough paper, then another 
layer of cloth, then paper, and so on until the insulation is 
nearly inch thick. Let each layer dry thoroughly before 
putting on the next, and make joints in successive layers in 
different places. Provide sixteen wooden wedges as shown in 
Figure 138. Make a radical slit through the insulation opposite 
the center of each of the armature projections, and press the 
wedges between the insulation and core for about two-thirds 

14 


210 


DYNAMO-ELECTRIC MACHINERY. 


their possible distance into the crescent shaped slots in the heads. 
Provide about 4 pounds of Number 9 (.114 inch dia.) double cotton 
covered magnet wire. Support the armature in a hoiizontal 
position and wind six turns around any one of the teeth ; let 
the beednninsf of the wire be on the collectoi side, and diaw 
each turn as tightly as possible. On account of the tapering 



sides of the projections the first turn will necessarily be at the 

bottom; the sixth will be near the top. Continue -a second 

layer of six turns on top the first, returning to the starting 

point; do not cut the wire but wind twelve turns around the 
next projection in the opposite direction ; then around the third wind 
in the same direction as on the first, and so on until the whole eight are 







































































HOW TO BUILD AX ALTERNATING CURRENT DYNAMO. 


Field Flang e 


Field 

Coil 


-Brass 

Strip 


J\rvn<xtu.re. Coil 


i -8 -32 «Scr& M 4. 

J\rmaXure, 

~FIcL'n-qe 



Ejamination 


FIGURE 145. 















































































































































































212 


DYNAMO-ELECTRIC MACHINERY. 


wound. The order in which they would then appear is 
shown in Figure 144. Make a number of thin tapering wedges 
of maple and drive them between the coils as shown in the 
end elevation of the dynamo, Figure 133, and more clearly in the 
larger view in Figure 137. Now drive the end wedges as far 
as possible into the heads; drill small holes opposite those al¬ 
ready in the iron, and insert ^ inch S-32 flat head screws. 
Figure 145 shows this detail of fastening. 

Remove all superfluous insulation from the surface of the 
core, and give the coils several coats of shellac. Lead the 
two terminal wires to opposite sides of the shaft, and bend them 
into small loops; cut off any extra length; slip the collector 
into place, and clamp these loops between the brass nuts and solder 
them to prevent loosening. 

Connections . The method in which the armature has been 
wound provides for their proper connecting. The field coils 
must necessarily have been wound alike, and if similarly placed 
on the poles should be connected as follows:—Beginning at the 
upper left hand coil, (viewed from collector end), leave the out¬ 
side end free, but connect the inner end with the inner of the 

next coil; then outer end with the outer end of the third coil, 

■ 

and so on, connecting inner to inner and outer to outer, until 
an outer end remains from the eighth coil, occupying the cen¬ 
tral upper position. The current should circulate in opposite 
directions around adjacent poles, so as to magnetize the iron in 
a regular succession of north and south poles. Send a current 
through the coils and test the polarities with a compass. Fig¬ 
ure 144 shows the proper arrangement. 

Three connection boards are provided. Their locations are 
clearly seen from reference to Figure 133. Details are shown in 


Plow TO BUILD AX ALTERNATING CURRENT DYNAMO 


2I 3 



























































































































































































214 


DYNAMO-ELECTRIC MACHINERY. 


Figure 146. A represents one for the main circuit, and B for 
the exciter circuit. Maple is good material for the bases, and 
the brass blocks are to be held by screws d , but the screws b 
and c enter the wood a short distance to keep the blocks from 
moving. Standard fuses of 20 amperes capacity should be con¬ 
nected in circuit. Those shown are soldered into copper clips, 
which in turn are clamped under the screw heads; good con¬ 
tact is thereby made, and ease of renewing secured. Screws 
a are for attaching the boards to the field magnet. The flex¬ 
ible cable should have a bundle of wires about inch diameter in all. 

A device shown at I may be used to connect the ends of 
different field coils together; two wires may easily be held in 
each clamp. The field terminal wires are to be soldered into 
clips B, and attached to the brass blocks on the exciter board. 
Main circuit wires leading to the switch board or lamps should 
be soldered into clips C, but it will suffice to bend the exciter 
circuit wires around the screws. 

Assembling and Using . Make sure that the electrical con¬ 
nections between the field coils are correct by sending the exciter 
current through and testing the polarities with a compass needle. 

After once having bored the field central with the bearings, 
it should not be removed from the base. Screw the pulley-end 
pedestal, with cap removed, in the position determined by its 
dowel-pins. Insert the armature, and screw down the collector- 
end pedestal, not forgetting to slip the oil-rings on the shaft. 
Slide on the linings for the bearings, letting the slots for the 
oil-rings come uppermost. Place the caps on the pedestals, and 
adjust the linings length-wise, so that the armature and field 
match, yet allowance be made for an end motion of ^ inch 
each way from the central position. Screw the caps down 









HOW TO BUILD AN ALTERNATING CURRENT DYNAMO. 21^ 

tightly, and run a drill through the f-inch holes a short distance 
into the linings. Remove the caps and drive pieces of f-inch 
steel rod into the holes so as to be flush with the outside and 
project about inch inside. Complete the holes through the 
linings and replace them on the shaft. Fit the collector-end cap 
with its studs, insulations, cable terminals, brush holders and 
brushes, and replace it; also return the pulley-end cap to its 
place and put on the pulleys. Attach the remaining ends of 
the cables to the main connection boards; connect exciter and 
line. Fill the reservoirs in the pedestal with light oil. Slip on 
the belts and allow the armature to run at full speed—2000 
revolutions per minute—half an hour or so before requiring it 
to generate, to make sure that the bearings are in good order. 

If it is necessary at any time to remove the armature, it 
may be done as follows: Remove the pulleys and caps; with¬ 
draw the collector-end lining; the pedestal may now be lifted 
high enough to disengage the dowel pins and allow it to be 
removed from the base. The armature can now be taken out 
end-wise. By following this method, the pulley-end bearing 
need not be disturbed. 

If pet-cocks have not been supplied, old oil may be with¬ 
drawn by removing the caps and inserting a siphon tube into 
the reservoirs. 

Any reliable continuous current dynamo, of about f horse¬ 
power out-put may be used for an exciter. If it be shunt or 
compound wound, the amount of current it supplies may be 
controlled by a rheostat inserted in the shunt circuit, but if it 
be series wound the rheostat must be so connected as to shunt 
a variable portion of the current into ciicuit without going 
around the field. Turn the main switch to have the lamps 


216 


DYNAMO-ELECTRIC MACHINERY. 




connected, and allow such an amount of current from the ex¬ 
citer, that the lamps will burn to the required brilliancy. If 
the number of lamps is changed considerably, an adjustment of 
the exciting current will be necessary. 

As a motor the machine is not self starting, unless some 
special devices, including a commutator, are introduced. \\ ith- 
out such attachments, the armature must first be rotated at full 
speed before the main switch is closed. For ease it is well to 
have the field circuit also open. When a speed above “syn¬ 
chronism’' has been reached, close the main and then the exciter 
switches, and the armature should immediately step into pace 
with the generator, and, within its capacity, run at a uniform 
speed independent of the load. A practical arrangement would 
be, to have the pulley on the main shaft, to which the motor 
is belted, held with a clutch. This pulley has, fastened to its 
spokes or hub, a smaller pulley which is belted to a larger 
wheel within reach from the floor. Turning this last with a 
crank, the armature may be easily driven at a high speed; then 
after the switches are closed, and the motor is seen to be run¬ 
ning, throw the clutch that connects the load. The speed at 
which the motor will run will depend on the “frequency” of 
the alternations in the generator. With a frequency of 125 per 
second, the usual rate, the motor will turn 1S75 revolutions per 
minute; with 133 cycles, the speed would be about 2000. 

For economy an ammeter should be inserted in the alternating 
current circuit, and after the load has been attached vary the 
amount of exciting current until that absorbed by the armature 
of the motor is a minimum. Use a thin pliable belt, and, 
if possible, let it run in a horizontal position. 


t 





types of commercial dynamos. 


2 I 7 


CHAPTER XIV. 

TYPES OF COMMERCIAL DYNAMOS. 

(direct CURRENT.) 

O F the many dynamos now in commercial use the author has 
selected those described on the following pages as standard 
kinds and best to use for examples of designs for description 

here. 

They are divided into two classes: (i) the direct current 

dynamo; (2) the alternating current dynamo. As the difference 
between alternating current and direct current machines has 
already been discussed in previous chapters, it will not be here. 
In this chapter we will take up the direct current dynamos. 

The Thomson-Houston Arc Dynamo , illustrated on page 
219, is remarkable for its construction. It was designed by 
Professors Elihu Thomson and Edwin J. Houston, of Philadel¬ 
phia. Originally its armature was nearly spherical and was 
wound with only three coils. The three coils were wound over 
the shell of the armature in three sets of windings, each layer 
being insulated from the shell and its neighbors. When the 
winding was completed the three ends of the free coils were 
carried through an opening in the shaft and attached to the three 
segments of the commutator. An illustration of the three part 
commutator is given in Figure 147. The field magnets are cup 


DYNAMO-ELECTRIC MACHINERY. 


2 iS 


shaped. They consist of two cast iron tubes, furnished at their 
inner ends with hollow cups cast in one with the tubes, and 
accurately turned to receive the armature. 

Upon these tubes are wound the coils; afterwards the two 
magnets are united by means of a number of wrought iron bars 
which constitute the yoke of the magnet and at the same time 
protect the coils. The magnets are carried on a framework, 
which also supports the bearings for the armature shaft. 

All late machines have ring armatures (see Figures 148-149- 
1^0), which are a great improvement over the old style (spherical 
armature) in the way of better ventilation, higher insulation, 



figure 147. 

greater freedom from burning out, and the ease with which faulty 
coils can be removed and new ones substituted. 

These armatures are interchangeable with the old style arma¬ 
ture, and can be used in any M. D. or L. D. machine. The 
commutator has only three segments in contact with which are 
four brushes. Regulation is obtained by an electro-magnet regu- 
lator, which controls the amount of current by automatic shifting 
of the brushes, in such a way that they short circuit one of the 
armature coils for a greater or less period of time, as the occa- 











































































































































































TYPES OF COMMERCIAL DYNAMOS. 














THOMS0N-H0UST0N ARC DYNAMO 




































































































































































220 


DYNAMO-ELECTRIC MACHINERY. 


COMMUTATOR END 



PULLEY END 



FIGURES 14 S AND 149 . 

























TYPES OF COMMERCIAL DYNAMOS. 


22 1 


sion may require, when from a reduction of resistance in the 
lamp circuit, by the extinguishing of a lamp, or otherwise, the 
current feeding the other lamps becomes liable to abnormal 
increase; this increase of current is made to flow through the 
coils of wire surrounding the iron core of the regulator magnet. 
The core becomes magnetized, causing the yoke to which the 
brushes are attached to be drawn up towards the regulator 
magnet, which changes the position of the brushes upon the 
commutator, so that they draw away from the maximum point, 
decreasing the potential; when more lights are turned on the 



figure 150. 

reverse action takes place. The current governing the legukitoi 
is cut in and out by means of a pair of electio-magnets teimed 
the controller magnets, and are connected with the legulatoi 
magnet of the dynamo. This controller, called a x\ ul 1 con¬ 
troller,” is shown in Figure 152. 

Sparking at the commutator is reduced by a blower, being 
so placed that it sends a current of air directly on to the point 



























22 2 


DYNAMO-ELECTRIC MACHINERY 



FIGURE ICJ2 




























































































































































































































































































































































































































TYPES OF COMMERCIAL DYNAMOS. 223 

of contact of the brushes and the commutator, which blows out 
the spark. An illustration of the Thomson blower is given in 
Figure 151. The largest machines have an electro-motive force 
of 3000 volts, and will maintain 63 arc lights in a single 
circuit. The ordinary machines, supplying 34 arc lamps at 45 
to 46 volts each, with a current of 9.6 amperes, has an internal 
resistance of 10.5 ohms in the armature and 10.5 ohms in the 
field magnet. 



figure 153. 

A diagram of the complete arc circuit of this dynamo is 
given in Figure 153. 

The Sperry Dynamo is illustrated in the engia\ing on 
page 224. 

In an analysis of the Sperry generator it will be seen that 
the wire which is to revolve in the presence of the field mag¬ 
nets is placed at a good distance from the axis of rotation in 
such a manner that a high peripheral velocity is obtained with 




































































THE SPERRY ARC LIGHT DYNAMO 

























































TYPES OF COMMERCIAL DYNAMOS. 


225 


a comparatively low rate of revolution of the armature shaft, 
theieby wasting as little as possible in friction at the journals; 
and depieciation of the wearing parts of the machine is avoided. 
Secondly, the presenting the greatest possible percentage of this 
generating conductor to the magnetic masses or pole pieces of 
the field magnets compels the induction in the space occupied by 
the generating conductor to be the highest possible, and at the 
same time makes the resistance of the magnetic circuit of the 
machine the lowest possible. 

The entire absence of overlapping of the coils is of great 
practical value. In case of injury sustained by one coil it will 
not cause the destruction of the whole armature, as the injured 
part can easily be removed and replaced without disturbing any 
other coil and without unwinding the whole armature down to 
this point, as in case of most forms of the cylindrical armature. 

The leaving of the inside of the armature free to the pole 
pieces is valuable for ventilation, and in thus keeping the arma¬ 
ture cool its electrical resistance is reduced and the danger of 
burning is avoided. 

The dynamos are so constructed as to be operated several in 
series upon a single circuit. This greatly reduces the expenses 

of construction, as modern practice in insulation admits of high 
electromotive forces being employed. The total - electromotive 
force upon the line being generated at several points is con¬ 

sidered more reliable than when generated within the terminals 
of a single machine. 

The plates of the armature core are made of thin iron, well 
annealed, and each carefully insulated from the other, and the 
whole mass supported by bolts which project from the edge and 

which are used to support the whole to the gun metal spider 

by means of which it is mounted upon the armature shaft. 


15 


226 


DYNAMO-ELECTRIC MACHINERY. 


The armature is covered with a coating of non-combustible 
and indestructible substance, the basis of which is asbestos. This 
substance has a very high insulating property, and cannot become 
charred by any temporary overload. The commutator is of the 
usual form, mica being employed as insulation throughout. It is 
very durable and of simple construction. The inventor claims 
that the brushes may be advanced from the position of full 
electro-motive force to even a position of zero voltage without 
sparking, the cross magnetizing action of the armature being 
small compared with the power of the field magnet. 

The Mather Electric Railway Generator . Recognizing 
the demand for power transmission by means of the electric 
current, the Mather Electric Company has brought out a series 

o 

of machines for that purpose. The generators are built up to 
30,000, 50,000 and 75,000 watts, with four poles, and 1 So,000 
watts with six poles. Drum armatures are used in all the 
machines. In the four-pole machines, the winding is such that 
the current has but two paths through the armature wires, and 
by a special method, devised by Prof. Anthony, no two wires 
having any great difference of potential are brought near each- 
other. The illustration represents the 75,000-watt generator, show¬ 
ing the general character of all the four-pole machines, with 
the field magnet in one casting. In the 180,000-watt six-pole 
machine, the field magnet is cast in two halves, but divided 
through the middle of two opposite poles instead of across the 
magnetic circle. 

The Thomson-Houston Joo-Horse- Power Generator . This 
is a multipolar dynamo—that is, it has four pole pieces, and has 
an output of 250,000 watts, which is equal to about 300 horse¬ 
power. The armature is of the Gramme ring pattern, and so 








THE MATHER DYNAMO. 







































































22S 


DYNAMO-ELECTRIC MACHINERY. 


constructed that opportunity is afforded for the best insulation, 
and the danger due to great difference of potential between any 
two of its conductors is avoided. This is a most valuable and 

inportant feature, as in case of accident or injury to any coil, 
it can be easily repaired without affecting in any way the re¬ 
maining coils. The construction of the armature affords excellent 
ventilation which is very necessary in dynamo machines, particu¬ 
larly as their size is increased, for the reason that the radiating 
surface does not increase in proportion to the size of the mass. 

One of the most important features of this generator is the 
arrangement for lubrication and good alignment of the bearings. 
The boxes are made in two parts, and are entirely 7 separate 
from the stands. On the top of the stand is a seat into which 
the spherical surface of the box fits, and in which the box is 

free to move. The bolts which secure it to the stand are smaller 
than the holes which are drilled through the box, so that a slight 
play of the box in the seat is permitted. The bearing shells or 
linings are removable, and are made in the following manner: 
A skeleton shell of brass is made, the interstices of which are 
filled with Magnolia metal. This is then bored and reamed to 

size, oilways being cut so that the oil circulation begins at the 
point where the oil rings touch the shaft. This method of 
manufacture permits of a perfect circulation of oil, ensures the 
cool running of the bearings, and greatly reduces the care and 
attention required by the dynamo when in operation. This type 

of box and bearing lining has proved so satisfactory that it is 
now being introduced in machines of smaller size, and will in 
future be used on all machines of large capacity. Whenever it 
is necessary to examine bearing linings, the armature is jacked 
up about y 6 of an inch, so that the bearing is relieved of its 













TYPES OF COMMERCIAL DYNAMOS. 


229 



THE THOMSON-HOUSTON 3OO-HORSE-POWER GENERATOR 






































































































































































































230 


DYNAMO-ELECTRIC MACHINERY. 


weight, two bolts removed from each stand, and the entire box 
taken out. In case it is not desired to remove the box, the 
cap can be taken off and the bearing linings readily removed. 

The movement of the brushes is affected by means of the 
shaft on which a small worm is attached, and which in turn 
works in a rack fastened to the yoke. By means of this a very 
fine adjustment of the bearings can be made. The worm locks the 
yoke so that it cannot be removed except by hand. 

In order that the conductors inside the armature may be 
held securely in place, an adjustable internal wire support has 
been designed. When the armature is being wound, the wires 
are forced into position so that they cannot sag, vibrate, or 
chafe the insulation. All tendency to short circuiting is thereby 
avoided, and the position of the wires assured. 

The commutator has 1S0 sections. In practice, the genera¬ 
tor will have its fields separately excited, although the connec¬ 
tion at the switch-board is so arranged that by throwing a switch 
the dynamo can be made self-exciting, should emergency require it. 

The total floor space occupied by the 300-horse-power gene¬ 
rator is 13 feet 3J inches by 7 feet 1 inch. The height of the 
machine is a little less than 8 feet. The pulley is 43 inches in 
diameter, and has a 35-inch face. The speed is 400 revolutions 
per minute, and the dynamo, complete, weighs about 21 tons. 

The Edison Direct Current Dynamo .—The field magnets 
consist of vertical cylinders with large wrought iron cores, which 
rest upon cast iron pole pieces and nearly enclose the armature. 
The armature is drum shaped. (See Figures 154 and 155.) 

The core consists of a number of sheet iron discs, insu¬ 
lated from each other by sheets of thin paper. The core is 
mounted on an iron shaft, but insulated from it by an interior 




TYPES OF COMMERCIAL DYNAMOS 


23I 


cylinder of lignum vitas, while an external covering of paper 
insulates it from the coils. The coils consist of cotton covered 
copper wire, stretched longitudinally and grouped together in 
parallel, a number of wires in a group, all of the group being 
so connected as to form a continuous closed circuit. The groups 



EDISON DIRECT CURRENT DYNAMO. 

are arranged in concentric layers, and are of the same number 
as the segments of the commutator, the ends of the wires in 
each group being attached to arms connecting with the commu¬ 
tator segments, a spiral arrangement being adopted in making 
the connections between the straight portion of the wire and the 





































































232 DYNAMO-ELECTRIC MACHINERY. 

arms. The object of grouping is to secure flexibility for winding 
by the use of small wire and low electrical resistance, by having 
several wires in parallel, the effect as to the resistance being 



practically the same as if the several wires were combined in 
one. At the ends the wires are insulated from the core by 
discs of vulcanized fibre with projecting teeth. The discs of the 
cores are bolted together by insulated rods, and the coils are 













































































































































































































types op commercial dynamos. 


233 


confined by brass bands surrounding the armature. The brushes 
aie composed of several layers of copper wires, combined with 
flat coppei stiips, two layers of wire being placed between each 
two stiips. d his arrangement is to give a more perfect con¬ 
nection, and to prevent sparking by furnishing numerous points 
of contact, the copper strips confining the wire and making the 
brush more compact. 

The ts/iort Electric Railway Generator , which is shown in the 
accompanying illustration is a very massive machine of 150 H.P., and 
is capable of delivering a current of 225 amperes at a pressure of 
500 volts. The field magnet frame is one large casting, weigh¬ 
ing over 3000 pounds, of soft iron slowly annealed. To this 
are bolted eight field magnets, carrying the shunt and series 
coils, and provided with pole pieces of peculiar shape, arranged 
for side presentation to the armature. The armature of this 
generator possesses distinctive characteristics, It is of the Gramme 
ring construction. The massive spider carrying the foundation 
ring upon which the armature is built, is keyed to a shaft nine 
feet long and six inches in diameter. The armature core is 
formed of thin sheet iron wound spirally on the foundation. By 
this method of winding, each of the 200 coils is exposed to the 
air on all sides, thus receiving perfect ventilation. The diame¬ 
ter of the armature is 36 inches. Another feature is in the 
commutator box, where there is an adjustable ball-bearing thrust 
collar, containing several hundred balls, and so arranged as to 
carry the armature thrust in either direction without heating. 
The commutator has 200 segments, so that the pressure between 
adjacent segments is unusually small, and there is no sparking. 
There are four brushes, which are held together by two inde¬ 
pendent collars and sets of brush holders. 




2 34 DYNAMO-ELECTRIC MACHINERY. 

































TYPES OF COMMERCIAL DYNAMOS 



2 35 

Crocker - Wheeler Multipolar Dynamo.~l\\ the multipolar 
type (illustrated) the steel magnets are turned to gauge and set 
into the yoke, the outer end of the holes for the fields being 
covered by a thin circular plate. The pillow block standards 


CROCKER-WHEELER MULTIPOLAR DYNAMO. 

are cast in one piece with the base, and the armature is ren¬ 
dered accessible by removing the caps of the bearings and the 
upper half of the magnet frame, thus permitting of the arma¬ 
ture being lifted vertically out of the bearings, when the upper 
half of the magnet frame is thus removed. The rocker arm is 






































DYNAMO-ELECTRIC MACHINERY. 


made in halves, held together by wing nuts, and travels upon a 
grooved ring attached to the pillow block standard, and slotted, 
the grooved ring being cut away through the upper side wide 
enough to permit the shaft to be lifted out. No solder is used 
in any part of these machines, and besides being built to stand 
25 per cent, overload without undue heating, they will stand an 
altogether unusual degree of heating without injury. 

The multipolar types above 25 H. P. (20 K. W.) for no 
volts have armature conductors of rectangular copper bars riveted 
together by means of strip copper and connectors, in place of 
the ordinary wire windings. These bars are insulated with mica 
and laid in slots in the armature core, so that they are pro- 



figure 156 


tected from injury or displacement and are practically free from 
danger of a burn-out. The armatures thus wound, although for 
multipolar machines, have but two circuits, and may therefore 
be operated with one set of brushes instead of two sets, because 
of the novel “series grouping” of the armature winding. The 
common practice in multipolar armature winding heretofore em¬ 
ployed renders one portion of the armature liable to short-circuit 
the other portions, if there is any inequality in the strength of 
the fields. This construction is an improved form of that for¬ 
merly followed by the Standard Electric Co., of St. Johnsbury, 





TYPES OF COMMERCIAL DYNAMOS. 


2 37 


Vt., of whom the Crocker-\\ heeler Company is the successor in this 
business. This form of armature was the invention of Mr. C. S. 
Bradley (see Figure 156), and was the prototype of all of the bar 
wound armatures now commonly made in large sizes, such as for 
railway generators, etc. 

General Electric Company's 150 K. IV. Belt Driven Railway 
Getierator. — While the direct coupling of railway generators to 
their prime movers is recommended in all cases where prime movers 
of suitable speed can be obtained, certain instances arise where 
belted connection is admissible and commendable. Conditions which 
warrant the use of belted machines are found in connection with 
water wheels of exceptionally low speeds, or with engines already 
in service, but of too good a speed for the economical construction 
of direct driven generators. 

The 100 K. W. and the 150 K. W. machines are made in the 
two-bearing form with the pulley overhung. 

All railway generators are compound wound, the series coils 

being wound in one end of the spool, and the shunt coils in the 

other; so that either can be unwound without disturbing the 

other. The series coils are wound with flat copper ribbon, and are 
placed at the outer, or yoke, end of the spools; the shunt coils are 
of wire, and are placed at the inner, or pole face, end of the 
spools. 

In machines which have a field winding of considerable depth, 
the winding is divided into two or more layers, separated by inter¬ 
vening air spaces, which extend through both the sei ies and shunt 
portions of the completed coils and register with openings in the 

end flanges. The centrifugal action of the armature blows air 





GENERAL ELECTRIC COMPANY’S 150 K. W. 


BELT DRIVEN RAILWAY GENERATOR. 





















TYPES OF COMMERCIAL DYNAMOS. 


2 39 


through these intervening spaces, thus greatly increasing the cooling 
surface and reducing the temperature of the field windings. 

The held spools are made up of sheet iron riveted to malleable 
iron flanges. 

The armature is built up of sheet steel punchings or lamina¬ 
tions, carefully annealed to reduce hysteresis, and japanned to insu¬ 
late them from each other, and thereby cut down the Foucault current 
losses. 

The laminations for all except the smallest machine are punched 
with dovetailed extensions, by which they are fastened in place on 
the cast iron spider. The laminations for the ioo K. W. machine 
are punched in one piece and keyed on to the shaft. At suitable 
intervals between laminations, space blocks are inserted, which are 
made up of steel strips set on edge and interlocked with the lamina¬ 
tions. These radial steel strips act as the vanes of a centrifugal fan, 
drawing air from an opening within the spider, driving it through 
the core, across the armature coils, and into and around the field 
coils, thus ventilating and cooling all parts of the machine. The 
laminations are forced together by means of circular cast iron end 
flanges, which are suitably extended to support the end connections 
of the armature coils. These cast iron flanges are cut away to 
reduce the iron losses, which would otherwise be set up in them 
by the currents in the armature coils. 

The armature coils are made up of copper ribbon, or bars, which 
are bent to shape before being insulated ; they are then individually 
taped. Insulation is inserted between the several strips or ribbons 
forming one coil, and the whole is wrapped with varnished cambric. 
The coils are further insulated from the core by means of insula¬ 
tion laid in the slots. 


240 


DYNAMO-ELECTRIC MACHINERY. 


The commutator construction is similar to that of the direct 
connected machines. A large number of segments per pole is used, 
and they are insulated from each other by mica of such thickness 
and softness that the commutator surface wears down uniformly. 

The front end of the commutator is cut away, so that the face 
of the commutator can be turned off without interfering with an 
end flange. A solid clamping ring is used on all sizes made for 
belt driving, and the same design of clamping ring is used at both 
ends of the commutator, the two being drawn together by several 
bolts. The interior of the commutator is ventilated by air passing 
through the spider to the air ducts in the armature core. 

Tivo Hundred Kilo- Watt Edison Generator. — In the accompany¬ 
ing illustration is shown the latest form of Edison railway genera¬ 
tor of 200 kilo-watt Capacity. As will be seen, it is of standard 
bipolar type, the general features of which are so well known as to 
need no further description. To adapt this generator to the demands 
of electric railway service, its field has been supplied with a com¬ 
pound winding, easily adjustable to meet the necessary requirements 
by means of a shunt coil, which is conveniently placed in the back 
board of the keeper. The close adjustment obtained by this arrange¬ 
ment greatly facilitates the operation of generators in parallel, and 
forms one of the characteristic features of this particular type. The 
series field is composed of sections wound on spools, which are 
slipped separately over the cores, and then properly connected. In 
the event of a fault occurring, the spool in which it develops can be 
removed and another substituted at once; this not only prevents 
delay, but makes any repairs necessary a matter of comparatively 
small expense. The armature is so wound that it has two distinct 
windings, and each end is furnished with its commutator, rocker- 



TYPES OF COMMERCIAL DYNAMOS 


24I 



16 
























































































































































































































































































242 


DYNAMO-ELECTRIC MACHINERY. 


arm and brush holders. The center of gravity of the armature is 
low, due to the bearings being located to the base frame, great 
stability is secured. Self-oiling bearings and carbon brushes help 
to reduce to a minimum the attention necessary to the operation of a 
dynamo. 

The General Electric Company's 800-K. IV. Dii'ect Connected Genera¬ 
tor. — The careful attention given the design of the large number of 
railway generators built by the General Electric Company during 
the past few years has resulted in constant improvements which 
have brought this lype of machine well toward the limit of attain¬ 
able perfection. The outcome of this constant development is a 
line of machines which operate sparklessly over a remarkable range 
of loads, are free from heating and burn-outs under all but the 
most severe abuse, give no trouble with a minimum of attention, 
and are practically free from all objectionable features. 

The Field Magnet. — The external circular yoke of the field, in 
all machines of this type, is made of cast iron, and has an oval cross 
section, except in very large machines, where it is cast with a box¬ 
like cioss section to give greater stiffness. The upper half of the 
field is fastened to the lower half by bolts entirely hidden within 
recesses cored in the side supports, thus doing away with side flanges 
and improving the appearance of the machine. 

The poles are solid steel castings with their outer ends ma¬ 
chined to fit accurately the planed faces projecting inwardly from 
the magnet frame. The use of circular poles of a solid material of 
high permeability minimizes the length of turns of the field winding, 
and reduces the waste in this part of the machine. 

Armature. — Each arm of the armature spider is cast with its 



TYPES OF COMMERCIAL DYNAMOS 


2 43 



COMMERCIAL DYNAMO AND MOTOR 



































































































DYNAMO-ELECTRIC MACHINERY. 


244 

own section of the spicier rim, ancl the rim sections are unconnected 
except through the hub, until the laminations are dovetailed to 
them; thus shrinkage strains in the castings are avoided. The 
arms have wings or fan blades cast to them, which are inclosed by 
deep extensions of the end flanges toward the shaft. These wings 
with the radial space blocks in the ventilating passages between the 
laminations, serve as a forcible centrifugal fan to keep a constant 
blast of air passing between the laminations and windings and 
around the poles, thus keeping all parts well ventilated and cool. 

The coils are of the usual form-wound copper strip type, held 
in the slots by wooden retaining wedges, which are sufficient for all 
ordinary strains, and also by binding bands over the ends, which 
gives added strength for emergencies such as a runaway of the 
prime mover. These binding bands are sectional and are fastened 
with a key, by means of which they may be readily removed or 
replaced. There are no binding bands on the armature surface 
under the poles. 

Dynamos for Electro-Plating .— Dynamos for electro-plating dif¬ 
fer from those in general use for electric lighting in a number of 
important particulars. The machines used for lighting purposes are 
wound so as to generate a current of high E. M. F., while a plating 
dynamo is constructed to give a current of large volume but of low 
E. M. F. The reasons are that a lighting circuit has a high resis¬ 
tance, while the resistance in a plating circuit is always low. A 
high E. M. F. is not desired in electro-plating, and this is overcome 
by using large wire in winding the dynamo, and running it at a low 
speed. The wires of the external circuit should be large too, so as 
to carry the current safely. 






TYPES OF COMMERCIAL DYNAMOS. 


2 45 


Among the many good dynamos which are well adapted 
for electro-plating are the following: 

The Wood Dynamo. The engraving gives a very good idea 
of the size and geneial appearance of the new improved ma¬ 
chine. It is of the Gramme type. In the armature of this 
machine we have a Gramme ring armature. The core is usually 
laminated, that is, it is made up of soft iron discs, insulated 
from each other by thin sheets of paper. These are mounted on 
a shaft. The insulated copper wire is wound in sections around 
the external and internal periphery of the ring. The beginning 



WOOD ELECTRO-PLATING DYNAMO. 


and ending wire of each section is left long, and when the 
ring is wound, the end of one section is twisted up with and 
soldered to the beginning of the next, and so on all around the 
ring. Then each twisted end is soldered to a separate bar of 
the commutator, of which there must be as many as there are 
sections in the coil. Four field magnets’ cores are used, so as 
to form the four corner yokes between two upright square cast¬ 
ings, which form the frame work of the machine. The two 
upper cores are connected to one pole-piece, and the two lower 







246 DYNAMO-ELECTRIC MACHINERY. 

to another. The field magnet coils are so wound as to pro¬ 
duce a north pole in the piece above, and a south pole in the 
piece below. The current is continuous, and well adapted to 
electro-plating. 

The Eddy Dyjictiyio electric machines for electro-plating and 
electro-typing have always enjoyed an excellent reputation. They 



EDDY ELECTRO-PLATING DYNAMO. 

have been modified and improved from time to time; the latest ones 
rank high for efficiency, simplicity and workmanship. In this 
machine the ring form of magnet (Mather patents) and Sieman’s 
armature is used. The field is always charged when the ma¬ 
chine is running, so deposition begins as soon as the connec- 





TYPES OF COMMERCIAL DYNAMOS. 247 

tion is made. Owing to the method of winding, it is impossible 
for them to reverse. 

Plug switches are placed on the bases of Numbers i and 
2, and the principle on which they work is to lessen the 
resistance ot the field, and so keep it from cutting out when 
heavily loaded. In using the switch, both plugs should be in 
the outside holes when running on a small amount of work, 
and as the work increases to the point where the deposition is 
slow, one plug should be put in the slotted hole marked No. 
1, and as the surface in the tanks is again increased, the other 
plug should be put in the hole No. 2. The No. 3 machine 
is controlled by switch as above, or by a separate exciter in 
special cases, and is under perfect control whether it is doing 
a small or large amount of work. 

The shafts are of tool steel, and are ground on dead centers, 
which insures uniformity. The bearings are of very hard com¬ 
position, and are, self-oiling; they contain flat rings which run 
on the shaft and carry oil from the reservoir below. The pet- 
cock under the bearing should be opened every morning and 
the old oil allowed to run out, then closed and refilled from 
the oil cups until it fills in the yoke at the end of the shaft, 
this should last all day. The bearings must not be allowed to 
run dry. Use a thin pliable belt, the full width of the pulley, 

and not have it drawn tightly. The pulleys are large enough 

to do the proper amount of work without being tight against 
the belt. A stiff, heavy belt would have to be drawn tightly, 
and would, in consequence, wear out the bearing sleeps. 

The commutator segments are solid, and extend down to 

the shaft, and with proper care will last a very long time. The 

brushes should be set so that the point of contact on the com- 


248 


DYNAMO-ELECTKIC MACHINERY. 


mutator of the top and bottom brushes shall be diametrically 
opposite. Adjust the brushes to insure a light but sure contact. 
Do not set them hard enough to cut the commutator. File the 
ends to a bevel that will bear flat on the commutator and keep 
t em so. Do not have the bevel at such an angle that only 
the front edge of the brush, or perhaps the corner, bears on 
the commutator. Such a condition of the brushes is liable to 
produce sparking. If they are properly trimmed and set, the ma¬ 
chine will run without sparks. Do not let the brushes and 
commutator get gummed up with oil. All the working current 
passes through the brushes and a good contact between brushes 
and commutator is indispensible. Keep the commutator clean. 
Do not deluge it with oil. Shift the brushes occasionally to a 
different place on the commutator, so as to wear all parts 
alike, and not cut channels or grooves in it. In setting the 
brushes, make allowance for the end shake of the shaft, and set 
them far enough from the end of the commutator so that there 
will be no possibility of contact between either brush and the 
commutator head. For lubricating the commutator, we recom¬ 
mend having a piece of felt which has been soaked in lard 
oil, and then had plumbago worked into it, which, if occasion¬ 
ally rubbed over the surface will keep it in good condition. 
A good oil for bearings is a 28-degree mineral oil. Under 
no circumstances use an animal or a vegetable oil. 

O 

The armature is supported in the magnet field by yokes 
supported by rods connected to the magnet, so rendering it impos¬ 
sible for it to get out of line. 






TAPES OI COMMERCIAL DYNAMOS. 


2 49 












800-K.W. DIRECT CONNECTED GENERATOR 




















250 


DYNAMO-ELECTRIC MACHINERY. 


The General Electric Company’s 8oo-k.w. mp. direct con¬ 
nected railway generator is shown on page 249. 

The Field MagJiet. The external circular yoke of the field, in all 
machines of this type, is made of cast iron, and has an oval cross 
section, except in very large machines, where it is cast with a box-like 
cross section to give greater stiffness. The upper half of the field is 
fastened to the lower half by bolts entirely hidden within recesses cored 
in the side supports, thus doing away with side flanges, and improving 
the appearance of the machine. 

The poles are solid steel castings with their outer ends machined 
to fit accurately the planed faces projecting inwardly from the magnet 
frame. The use of circular poles of a solid material of high permea¬ 
bility minimizes the length of turns of the field winding, and reduces 
the waste in this part of the machine. 

Armature. Each arm of the armature spider is cast with its own 
section of the spider rim, and the rim sections are unconnected except 
through the hub, until the laminations are dovetailed to them; thus 
shrinkage strains in the castings are avoided. The arms have wings 
or fan blades cast to them, which are enclosed by deep extensions of 
the end flanges toward the shaft. These wings with the radial space 
blocks in the ventilating passages between the laminations, serve as a 
forcible centrifugal fan to keep a constant blast of air passing between 
the laminations and windings, and around the poles, thus keeping all 
parts well ventilated and cool. 

The coils are of the usual form-wound copper strip type, held in 
the slots by wooden retaining wedges, which are sufficient for all ordi¬ 
nary strains, and also by binding bands over the ends, which gives added 
strength for emergencies such as a runaway of the prime mover. These 
binding bands are sectional and are fastened with a key, by means of 
which they may be readily removed or replaced. There are no binding 
bands on the binding bands on the armature surface under the poles. 




TYPES OF COMMERCIAL DYNAMOS. 


2 5 1 


CHAPTER XV. 

TYPES OF COMMERCIAL DYNAMOS. 

( ALTERNATING CURRENT.) 

T HE high potential alternating current system was introduced 
into the United States in 1885. Since that time it has been 
continuously developed and improved. On the following pages 
will be found descriptions of the various machines manufactured 
by the most prominent manufacturers of the present day. 

The Drush Alternating Current Dynamo. The underlying 
principle of the remarkable “coreless” dynamo here illustrated was 
discovered and applied by Mr. Brush. 

The first glance at the dynamo shows that it is novel, compact 
symmetrical and strong. A brief examination shows that it is 
of the alternating type; that its field magnets are many and 
carried by the shaft; that the armature is fixed and absolutely 
free from any magnetic material; that its parts are easily access¬ 
ible, and that an armature coil may be cut out, removed or 
replaced without stopping the machine. 

The machine chosen for illustration and description has an 
output of 60,000 watts; it supplies current for a thousand 16- 
candle power lamps. 

The shaft bearings, bearing standards, base plate and arm¬ 
ature slides are cast in one solid piece. The center line ot the 
shaft is 16^ inches above the surface of the base plate, high 


252 


DYNAMO-ELECTRIC MACHINERY. 


enough for access to all parts of the dynamo ana low enough 
for steadiness and freedom from strain on foundations. The 
4-inch steel shaft (tapering to 3J inches in the bearings) carries 
two heavy cast iron yoke pieces, 27 inches in diameter. To 
each of these are screwed, at equal radial and circumferential 
distances, the wrought iron cores of twelve magnets of alternating 
polarity. The two yoke pieces, with their bolts, washers, etc., 
weigh about 950 pounds; the magnet cores, 30S; the magnet 
wire, 400. Thus the whole rotating mass of cast iron', wrought 



THE BRUSH ALTERNATING CURRENT DYNAMO. 

iron and copper, acts as a fly wdieel weighing more than 1,700 
pounds, and tending to neutralize any variation in the speed of 
the prime generator. As the nominal speed of the machine is 
fewer than i,too revolutions per minute, the structural strength 
is more than sufficient to meet all demands made by centrifugal 
force. Further than this, the mechanical stress is less wdien the 
magnets are excited than when the alternator is running without 
load, as the lines of magnetic force between the faces of oppo¬ 
sing poles, tend to counteract the centrifugal force. 

But the most interesting part of the alternator is the fixed 
armature, shown in the engraving (Figure 157). The vertical disc 









TYPES OF COMMERCIAL DYNAMOS. 


figure 157* 





































































































254 


DYNAMO-ELECTRIC MACHINERY. 


is occupied by flat armature coils, made of insulated copper rib¬ 
bon wound on porcelain cores. The copper ribbon of each coil 

is reinforced on either side with strong insulating material of the 
same thickness as the porcelain. One of these reinforcements is 
grooved and the other tongued. The coil consisting thus of core, 
ribbon and reinforcements, has an angular width of 60 degrees, 
the upper part of each face of each coil, is covered with an 

insulating plate of an inch thick. The coil thus built up 

and insulated is set in German silver holders, cut from true 
turned rings and held together by sunk headed screws, as shown 
in the engraving. Each terminal of the copper ribbon connects 
with a binding post as shown. 

The six armature coils thus mounted are carried in a Ger¬ 
man silver frame consisting of two semi-circles bolted together 
on the line of the vertical diameter. The cross section of this 
ring frame is girder-like. Into the slots of the frame slip the 

six mounted armature coils the tongue on the edge of the one 
engaging with the groove on the edge of the next. The coils 
thus thrust into the intense magnetic field constitute a disc, T 9 g- 
of an inch in thickness, and with an opening in the center 
through which passes the revolving shaft. As there is no mag¬ 
netic metal in the armature there are no local currents to waste 
the energy. 

The several coils are insulated carefully, and the stationary 
armature, as a whole, is is insulated from the bed plate on which 
it rests. The coils are joined in series, the binding posts adja¬ 
cent to any radial line of division between the two coils consti¬ 
tuting fixed terminals for the main line. There is no commuta¬ 
tor; there are no collecting brushes to take the alternating cur¬ 
rent from rotating parts. 




TYPES OF COMMERCIAL DYNAMOS. 


2 55 


The low resistance of the armature coils is evident. It would 
seem impossible for one of them to burn out; none ever 

have burned out. But if one should, it may be removed and a 
new one readily put in its place in three minutes, or the injured 
coil may be shunted out of the circuit and the dynamo kept 
running with the other five until the time for shutting down. 
The coil section complete weighs only about 20 pounds. 

In action, the 24-field magnets of the alternator are excited 
by the direct current from an 11-inch Brush dynamo of 
the well known form. This exciting current is carried to the 
brushes that rest upon the two uncut insulating rings, and 
thence through the hollow shaft to the magnets. A rheostat 
worked by hand or automatically is placed in the shunt circuit 
around the field magnets of the exciter, so that perfect regula¬ 
tion is secured without readjustment of the brushes or any nec¬ 
essity of handling the high-tension alternating current. 

The Brush Pfannkuche “coreless” alternator is built at pres¬ 
ent for an E. M. F. of 2000 volts. 

The Thomson-Houston Alternating Current Dynamo shown 
in the illustration differs very materially from the well known 
types of machines made by this company, but has the same 
characteristics of excellence and embodies new and oiiginal ideas 
in dynamo design. 

The Thomson-Houston company recognizing the advantages of 
automatic regulation have produced a machine that, differing fiom 
any other on the market, is self regulating for all changes of 
load, keeping the lights at a constant brilliancy. This is accom¬ 
plished by an arrangement of the coils on the field magnets of 

a dynamo, called a “composite field. 

A part of the magnetic field is maintained by means ot cur- 





































































































































TYPES OF COMMERCIAL DYNAMOS. 


2 57 


rent from a separate or exciting dynamo. If the load upon the 
outside circuit is increased, it is necessary to increase the masr- 
netism of the field in order that the machine may in turn sup¬ 
ply the increased demand in the circuit and the lights remain 
steady. 

This is accomplished in other machines by varying the cur¬ 
rent on the field magnets by a rheostat or variable resistance 
by hand. In the Thomson-Houston Dynamo, however, the same 
result is obtained entirely automatically by passing the greater 
portion of the main current through two or more field magnets, 
thus energizing the machine in exact accordance with the de¬ 
mands made upon it. As an alternating current is not suitable 
for magnetizing the fields, it is necessary to change the character 
of the current before passing it through the special winding on 
the field; and this is done by a' commutator at the end of the 
shaft. By this regulation the attention required at the dyna¬ 
mo is reduced to a minimum, while at the same time the effi¬ 
ciency of the machine is increased, and any number of lamps 
from one to the full capacity may be thrown on or off with¬ 
out in any way affecting the steadiness and brilliancy of those 
remaining. 

To allow for a pre-determined percentage of loss in the 

wiring, it is necessary as the load is increased, that there should 

% 

be a definite amount of increase in potential, which is accom¬ 
plished by placing around the field winding for the main current 
a resistance which shunts that portion of current not required for 
regulation. 

The coils for field magnets are wound on spools which are 
slipped over the castings and fastened firmly in position. These 
being well protected, the liability of mechanical injury is reduced 


17 



FIGURE 158 


SHUNT 
















































































































































TYPES OF COMMERCIAL DYNAMOS. 


2 59 


to a minimum. In case it is necessary to replace a coil or to 
lemove the ai mature, the upper half of the field casting can be 
readily removed, leaving the parts easily accessible. 

The potential of the alternating current requires that the 
utmost care be used in design and construction of the armature. 
It is wound with one layer of wire, ample provision being made 
for insulation between the wire and the iron core, as well as 
between the separate coils of which this layer is composed. 

These coils are carefully covered by a material possessing high 
insulating and protective qualities, and the whole is held in 
place by bands very firmly wound and fastened. The form of 
the core is such that perfect ventilation is secured, thereby en¬ 
tirely obviating any tendency to overheating. 

The collectors consist of two copper rings from which the 
current is conducted by means of narrow brushes, which require 
no adjustment, beyond that of the tension springs governing the 
pressure of the brush on the collector ring. 

The dynamo is supplied with a cast iron base, or bed plate 
which is provided with a rachet belt tightener. 

For the purpose of energizing the field magnets, the dyna¬ 

mos are furnished with small exciting dynamos of the direct 
current type. It has been found desirable in some special cases 
to make the smaller sizes of the alternating current dynamos self 
exciting, and to this end the armatures are wound with an extra 
or special coil for furnishing current to energize the fields. 

The exciter is usually placed as shown in the cut, behind 
the alternating dynamo, driven by a belt from a small pulley 
attached to the armature shaft. One exciter is usually employed 

with each alternating current dynamo, but when several dynamos 
are operated in the same station it is often found more conven- 


2 Go 


DYNAMO-EI.ECTRIC MACHINERY. 


ient to employ exciters, any one of which is of sufficient capac¬ 
ity for all the machines. By this arrangement an accident to one 
exciter need not affect the general service. 

As previously stated, when lights are required to be sup¬ 
plied at different degrees of voltage or pressure it is necessary 
to use what is called a transformer, which is made on the 
principle of the induction coil, having two coils, a primary and 
secondary, and is operated by induction. By induction we mean 

“A current is said to be induced in a conductor when it is 

/ 

caused by the conductor cutting lines of magnetic force. A 
fluctuating current in a conductor will tend to induce a fluctua¬ 
ting current in another running parallel to it. A static charge 
of electricity is induced in neighboring bodies by the presence 
of an electrified body. A magnet induces magnetism in neigh¬ 

boring bodies.” 

By sending the current from the dynamo through the smaller 
or primary wire, the voltage is lowered in the secondary coil 

with a corresponding increase of quantity, or by sending the 
current through the larger or secondary coil; the current in the 
primary coil is raised in voltage but is less in quantity. 

The two coils are carefully insulated from each other and 

from the iron core, thus preventing the high potential current 
from reaching the secondary or house line. As an additional 
security in case any such connection is made, there is included 
in the secondary wiring of each transformer a Thomson automatic 
protective device, which, in case of contact between the primary 
and secondary coils, will cut the transformer out of the circuit. 

Transformers are made which may be used in connection 
with lamps of either 52 or 104 volts, it being only necessary 

to change a connection in the transformer for a change in the 





WESTINGHOUSE CONSTANT POTENTIAL ALTERNATING CURRENT GENERATOR. 





262 


DYNAMO-EEECTRIC MACHINERY. 


potential of the secondary circuit. A weather proof iron case 
contains the transformer, with the necessary safety fuses and 
connections for the primary and secondary wires. A special 
arrangement makes it possible to cut the transformer out of cir¬ 
cuit while replacing fuses. 

The station transformer is used for supplying current for the 
potential indicator and lamps upon the switchboard. 

A diagram of a composite field piece and connections is 
given in Figure 158. 

WestinghouseCo?istant Potential Alternating Cur rent Dynamo. 
To the practical central station manager the accompanying illus¬ 
tration of the constant potential alternating current generator will 
at once commend itself. The main frame of the machine is in 
two parts, securely bolted together, and which-separate on a hor¬ 
izontal plane. The upper piece, or yoke, can be readily lifted 
off for inspection or repairs without the dynamo base being in 
any way disturbed. The whole design is rigid, and the pole 
pieces projecting radially inward are in such a position, and are 
so proportioned, that there is almost no external field, the entire 
exciting current being utilized with a minimum waste of energy. 
Ball bearings give a perfect alignment to the armature shaft, 
there being a self-oiling chamber to secure perfect lubrication 
at each bearing. 

With the rapid growth of the electric lighting industry, and 
the establishment of central stations to supply the needs of our 
large cities, has come a demand for a system of combined incan¬ 
descent, arc and power service, to meet which has been designed 
a line of generators operating at the rate of 7,200 alternations 
per minute, 16,000 alternations having been the exclusive prac¬ 
tice in the past. The result accomplished by this reduction in 
the number of alternations are briefly as follows: 




€.■Uuiiiphasc or- Tesla System 
Tcmismiesi on rurti JJish 'i bn l ion. 





FIGURE 159 































































































































































































































































264 


DYNAMO-ELECTRIC MACHINERY. 


Following the natural course of improvement in mechani¬ 
cal, as well as in electrical design, has come a demand for 
slower belt speeds, easy running machinery, and great economy 
of floor space. At 16,000 alternations per minute the number 

of pole pieces required, in order to reduce standard speeds, is 

so great as to make the machines heavy, cumbersome and expen¬ 
sive, especially as the speeds are reduced to an extent which will 
permit the direct connection of the generator to an engine or tur¬ 
bine shaft. The latter condition is one requisite in order that 
the minimum floor space may be attained, and such connection 
is in many cases possible with the 7200 alternation generators. 

The Tesla Polyphase System lends itself to every purpose 
for which electrical power is used. It may fairly be called a 
universal system. It is equally adapted to supply light or power. 
It will supply arc lights or incandescent lamps. It furnishes 
power through motors of the rotary field type or of the poly¬ 
phase synchronous type. 

By means of commutating devices, direct or continuous cur¬ 
rent is readily obtained for the operation of street railway sys¬ 

tems, for electrolytic work, and for all other purposes requiring 
this kind of current. 

By it we may use alternating current for transmission, and 
may readily obtain either alternating or direct current at practi¬ 
cally any potential adapted to any purposes to which electricity 
is applicable. 

The universal application of the system is illustrated in 
Figure 159, on page 263. The generators A and B, are located at 
the generating station, and are driven by turbines. Each gener¬ 
ator delivers two distinct alternating currents to raising transform¬ 
ers, RT, RT', RT", RT'", through the switchboard D. The cur- 



TYPES OF COMMERCIAL DYNAMOS. 


265 

rent, as generated, is of low potential, and may be handled with 
entire safety, but the raising transformers deliver their currents 
to the transmission circuits, L, L/, L", L" 7 , at a very high poten¬ 
tial, e. g., 10,000 volts. At a point conveniently located with 
reference to the district where lights and motors are to be sup¬ 
plied, a sub-station is erected. The transmission circuits enter 
the station and deliver their currents to the step-down or reduc¬ 
ing transformers, LT, LT 7 , LT 77 , LT ", which, in turn, deliver 
currents at moderate potentials suitable for local distribution. 
The switchboard, F, affords means whereby the circuits coming 
from the various groups of lowering transformers may be readily 
transferred and interchanged, so that any of the transmission 
circuits may be used to supply any of the local distributing cir¬ 

cuits, as may be advantageous or convenient. In the diagram, 
beginning at the left of the switchboard, the first four-wire cir¬ 
cuit is used to supply alternating current to the motor generator or 
rotary transformer, MG, which, in turn, delivers direct current 
at 500 volts to a trolley line, from which the street car, K, is 
supplied. The second circuit supplies the motors, M, M 7 , M 77 , M 777 , 
—of the two-phase synchronous type, or of the rotary field type, 
—which are adapted to general power purposes in mills, facto¬ 
ries, etc. The next four-wire circuit is divided into two two- 

wire circuits, and is used to supply incandescent lamps through 
the transformers, b, V, b 77 . The next circuit supplies alternating 
current to the motor generator, MG", which delivers direct cur¬ 
rent for arc lighting purposes. The last circuit shown supplies 
the motor generator, MG 7 , which, in turn, delivers diiect cuilent 
at low potential for electrolytic purposes, as indicated in the vats, 
V, V 7 , V", V 777 . If the frequency employed be sufficiently high, 
(say 50 periods per second, or 6000 alternations per minute) 


DYNAMO-ELECTRIC MACHINERY. 


2 66 

constant potential alternating current arc lamps may be supplied from 
the secondary circuits of transformers. 

There are several types of two-phase alternating current gene¬ 
rators, among which two are especially prominent. Machines of the 
first type are really double machines, having two fields and two 
armatures, — the latter mounted on the same shaft. Each armature 
delivers alternating current to a two-wire circuit, and these circuits 
taken together constitute the four-wire circuit of the generator, or they 
may be so connected as to constitute a three-wire circuit. 

Machines of the second type have single armatures with two 
windings, or with a single winding so connected to the ring collectors 
as to deliver two currents differing in their time relation or phase. 
The machines of this type are very similar in appearance to the direct 
connected generators. In place of the commutators ring collectors 
are used, but in other respects the construction is not materially 
modified. 

Field Magnets for Dynamos. For the convenience of the reader, 
an illustration of a number of different styles of field-magnets is given 
on page 267. In many cases the structure which acts as a magnet has 
also to do duty as a framework, which involves considerations that 
may interfere with the magnetic circuit. But the rule is to seek for 
the circuit of highest permeability. This will consist of the most com¬ 
pact form, greatest cross section, softest iron, and fewest joints. 






TYPES OF COMMERCIAL DYNAMOS. 


267 





SOME VARIOUS FORMS OF FIELD MAGNETS (ALTERNATING 

AND DIRECT CURRENT). 






























268 


DYNAMO-ELECTRIC MACHINERY. 


CHAPTER XVI. 

TYPES OF COMMERCIAL STATIONERY MOTORS. 

O F the many kinds of stationary motors we select and give the 
following : 

The Lundell Motor. These motors are made in six sizes, 
ranging in power from ^ of one horse-power to 5 horse-power, 
being wound for 115, 230, or 500 volt circuits, as desired. 

The amperes taken at full load and 115 volts range in the 
six sizes from 2.2 to 45. 

The Interior Conduit Company claims that in some respects 
these power motors are superior to the fan motors manufactured 
by them, and that their merit consists in the high development 
of the factors of high efficiency, simplicity, compactness, light¬ 
weight, cleanliness, and neatness of appearance. In these motors 
the company has been enabled to incorporate some qualities not 
obtainable in the fan-motor size; as, for instance, by the simple 
fact of increased dimensions the form becomes cylindrical and 
this permits the placing of the field coil concentric with the 
armature instead of at an oblique angle. The concentric position 
of the field coil permits the withdrawal of the armature without 
disturbing pole-pieces—a very great advantage in motors of any 
considerable power. A further modification is obtained in plac¬ 
ing the commutator outside of the field magnet shell, but well 
protected between the two limbs of a broad and strong bracket. 




COMMERCIAL STATIONARY MOTORS 


269 



THE LUNDELL MOTOR 

































270 


DYNAMO-ELECTRIC MACHINERY 



POLE PIECES 























































































































COMMERCIAL STATIONARY MOTORS. 


271 

This change of commutator position is made for the purpose 
of affording the ready access to brushes and commutator demand¬ 
ed by motors employing a current of any considerable quantity. 

The brush-holder as well as the commutator are of superior 
design and workmanship, the former being extremely simple, 
enabling the renewal and restoration of a brush with great ease 
and in a second or two of time. The armature is of excellent 
design and workmanship; it is substantially built and combines 
maximum cross sections with minimum length of wire. This, 



THE ARMATURE-LUNDELL MOTOR. 


the company claims, secures high efficiency and low speed vari¬ 
ations between extremes of load. This is a shunt-wound motor, 
in fact, which practically fulfils the duty and office of a differ¬ 
ential motor. 

In regard to the bearings, the same careful attention has 
been given as to the other parts. They are self oiling and pro¬ 
vided with a vision gauge by means of which the condition of 
the oil supply can be seen at a glance. The bushings are made 
of the best material and are easily removed and renewed when 
worn out. 

Each motor is furnished with a Lundell regulating and start¬ 
ing box or a Carpenter enamel rheostat as desired. The advan- 








































272 


DYNAMO-ELECTRIC MACHINERY. 


tage of the latter is that it occupies a very small space; it is 
also fire-proof and water-proof and is mechanically strong and 
simple in construction. 

The Jenney Automatic Electric Motor , illustrated on page 
273, shows one type of the constant potential motors. This 
machine is widely different from those in general use, the arm¬ 
ature, field-magnet and shape of pole pieces being its charac¬ 
teristic features. 

The aim has been to produce a magnetic field of enormous 
strength, which will, at the same time, be economical to maintain. 
By studying the direction of the magnetic lines of force about a 
straight bar magnet, the inventor was led to design the form of 
magnet shown. The natural direction and curvature of the lines of 

force, as they pass through the air from one pole to the other in 

a bar magnet, are well known. In this machine the pole-pieces 

were made to correspond with the natural curvature of the lines of 

force, thereby reducing to a minimum the length of the magnetic 
circuit, and its resistance. 

There is but a single field magnet, and in all sizes the core 
is made of the softest wrought iron. No yokes are needed. 
The pole-pieces are made of soft cast iron of the best quality for 
the purpose. There are no projecting ends or corners, with their 
attendant loss of magnetism. The cores extend entirely through 
pole-pieces, which are bored to fit them accurately. The pole- 
pieces are then slotted, and by means of bolts are firmly clamped 
to the core. By this means the largest possible surface contact is 
secured, and a most perfect magnetic union, with an extremely 
small amount of magnetic resistance. 

The armature is of the drum type, and is built up of thin discs, 
all of which are securely fastened to the shaft. The winding is 



COMMERCIAL STATIONARY MOTORS. 2^3 

a modification of the Siemens method, and the armature is so 
proportioned that it has but little idle wire over the ends. The 
electrical resistance is very low, and there are but few turns 
to each section. It is wound with the greatest care, and so insu¬ 
lated that there is little danger of short-circuiting and burning 
out. The ends of the armature, and the electrical connections, 



JENNEY AUTOMATIC ELECTRIC MOTOR. 


are thoroughly covered, thereby protecting them from copper dust 
or dirt of any kind. 

The commutator is insulated with mica, and is of ample width 
of face to secure the best action and reduce the wear to a mini¬ 
mum. 


18 












































2 74 


DYNAMO-ELECTRIC MACHINERY. 


The shaft is of the best grade of machinery steel, of greatest 
diameter in its central part, accurately turned, and finished in 
the best manner possible. All armatures of the same class are 
interchangeable. 

All motors above one horse power are supplied with a double 
set of brushes, so that the brushes may be turned or changed 
without stopping the motor. All parts are made after fixed 
standards and are interchangeable. 

The proportioning of the magnetic parts and the windings 
of the motor is such as to give automatic regulation of speed 

which is practically perfect, without compound windings of any 
kind. When the brushes are properly set there is no sparking 
at the commutator, even under severe changes of load. This 
removes the necessity for constant attendance, and makes the 
motor absolutely automatic. The field magnet has a simple shunt 

winding, so that if a sudden and heavy load is applied, the motor 

will not reverse its polarity and tend to run backward, as is 

the case with the compound wound motor. 

The Eddy Motor. This motor is designed on the general 
principles of construction of the Mather type. In this latter form, 
it will be remembered that the field is a ring; consequently the 
field coils cannot be wound in a lathe, and the length and numer¬ 
ous turns of fine wire, required for a shunt machine, makes the 
winding by hand tedious and difficult. It it common to wind 
a considerable number of wires in multiple, then connect them 
finally in series to give the requisite resistance; for high poten¬ 
tials this practice is not reliable. 

The Eddy Company, while preserving * the general excellent 
ring form of field by use of large round corners have made the 
coils straight. They can easily be wound in a lathe, using but 








COMMERCIAL STATIONARY MOTORS. 


2 75 

one wire and insulating between the layers. Wires having large 
differences of potential between them do not cross each other. 
They can safely be wound for all commercial voltages, and attain 
at a reduced cost, the same high efficiency as the Mather type. 
The amount of current in the field magnet coils is therefore very 



EDDY 15 H.-P. AUTOMATIC ELECTRIC MOTOR. 

small. The magnets do not get warm. The watts consumed in 
charging the magnets of a motor bear no relation to the work 
done by the armature, and as far as the efficiency of the motor 
may be concerned may be said to be wasted. It is therefore 
extremely important to reduce this magnetising current to a min¬ 
imum in order to produce an efficient motor. At the same time, 
it will be seen, high efficiency in a motor requiies a stiong 
magnetic field. 











































276 


DYNAMO-ELECTRIC MACHINERY. 


The Crocker- Wheeler Electric Motor , of which two illus¬ 
trations are given, possesses some special features of merit which 
are as follows: 

The field magnets are composed of the best wrought iron, 
each magnet be ng forged in a single piece, and set deeply into 
the base in order to secure solidity and ample magnetic contact. 
The space for wire on these magnets is perfectly cylindrical, in 



CROCKER-WHEELER ELECTRIC MOTOR. 


the form of an ordinary spool, thereby insuring smooth and per¬ 
fect winding of the wire, and is short in length, permitting 
the shaft of the machine to be low enough to free it from 
vibration. By this construction the neutrality or freedom of the 
base from magnetism is secured, and there is no tendency to 
leakage. This is claimed to make the machine much superior to 








































































COMMERCIAL STATIONARY MOTORS. 


277 

those in which the base is made to serve as one of the pole 
pieces, as the bearings then become magnetized and make the 
shaft bind. 

•The armatures contain several improvements. They are suffi¬ 
ciently large in diameter to obtain slow speed, and are so 
designed that the wire winding is entirely embedded below the 
surface of the iron core, thus protecting it from all injury, 
holding it rigidly in position, and rendering it possible for the 
magnets to approach very closely to the core, so that an in¬ 
tense magnetic effect is produced. The armature is fastened upon 
a brass face-plate, which is first turned perfectly true, and after 
completion the armature is very carefully balanced, so that when 
run at full speed the motion is hardly perceptible. 

The bearings are all of the self oiling type, which do not 
require attention oftener than once in two to four weeks. 

The base of the pillow block is hollow, and contains a 
supply of oil which is carried over the shaft by two rings which 
travel upon the latter, and are caused to revolve by its motion. 
They dip in the oil and carry it continuously to the upper side 
of the shaft. 

The bushings in which the shaft runs rest in turn in uni¬ 
versal or ball joints in seats of babbit metal in pillow blocks, 
so that the bearings are sure to assume perfect alignment when 
the shaft is introduced. After the motor has run a month, the 
old oil containing the grit, etc., should be drawn off from the 
pet-cock at the base of the pillow block. The cock should then 
be closed and fresh oil introduced by removing the thumbscrew 
in the pillow block cap on top. 

The brushes are held by rocker arms which can revolve 
freely around the entire circle, without fear of the brass con- 



SKELETON VIEW—SHOWING INTERNAL CONSTRUCTION, 
CROCKER-WHEELER ELECTRIC MOTOR. 

much wire as is used on the fields of the ordinary standard machines, 
d his great saving of wire not only reduces the weight of the 
machine, but materially increases its efficiency, or the amount of 
power that can be obtained from a given amount of electricity, 
for with less wire less electricity is required. 


278 DYNAMO-ELECTRIC MACHINERY 

necting parts “grounding” against the frame, a great advantage 
in special work where motors are to be adapted for use in 
unusual positions. 

With this form of armature core which reaches close to" the 
field magnets, and the high grade of wrought iron used for the latter, 
it is claimed they are enabled to maintain the magnetism and 
therefore the power of these motors, with only about one-third as 
























































































































COMMERCIAL STATIONARY MOTORS. 


279 

The speed of the motors is very low, which in many cases 
makes countershafting, etc., unnecessary. 

The proximity of the armature core to the field magnets ren¬ 
ders a high magnetic pressure unnecessary, therefore the magnetism 
escaping from the fields is very much reduced. 

Double insulated wire is used throughout for the windings, 
the cores being first wrapped with oiled paper and heavy can¬ 
vas saturated with shellac. 

The rocker arm is provided with a heavy insulated handle 
to enable all adjustments to be made without touching the con¬ 
necting parts, and the entire machine is heavily japanned and 
baked at a high temperature, thus securing a polished surface 
which resists dirt and oil. 

In connection with their incandescent motors, they furnish 
fireproof and indestructible regulating boxes for starting, stopping 
and varying the speed of the machines. These are built entirely 
of slate, china and iron. The arrangement of contacts in the 
switch on top of the regulator is such that both the field and 
armature of the motor is charged by the single operation of 
turning the knob, making it impossible to put the current on the 
armature before the field is charged, which has so often been 
the cause of the accidental burning out of many motors by the 
use of ordinary regulators. 

The field is first charged through a small resistance coil 
which is put in for the purpose of preventing a too sudden 
change in the magnetic strength of the latter, as well as to 
divide the spark when the motor is disconnected. The coils used 
for starting the armature are all of the same size wire carefully 
tried for carrying the full current of the machine at all speeds. 
With the fireproof regulator, the motor can therefore be slowed 


280 


DYNAMO-ELECTRIC MACHINERY. 



down and left running at any desired speed, indefinitely, and the 
usual caution “never to leave the box half turned on for fear of 
overheating and fire,” is unnecessary. 

The Thomson Houston Stationary ]\Iotor. The 15 horse¬ 
power motor shown in the illustration has an average commercial 
efficiency when fully loaded of 91 per cent. This high efficiency 


THOMSON-HOUSTON STATIONARY MOTOR. 

is obtained by paying careful attention to the electric and magnetic 
proportioning of the motor. 

The magnetic circuit is very short and of ample section, and 
therefore of low resistance, and the magnetic poles are so formed 
as to convey the magnetism into the armature with the least pos¬ 
sible loss. As will be noted in the engraving, the poles of the 








COMMERCIAL STATIONARY MOTORS 


26 I 


field magnets, the bodies or cores of which are round in section, 
project upward, enclosing the armature. The armature is nearly 
square in longitudinal section and relatively large in diameter. 

This gives a high peripheral velocity and a rapid cutting of the 
lines of force. In consequence of this construction, also, the 
armature is capable of exerting a powerful rotative force. The 
armature being short, avoids the use of a long and consequently 
less rigid shaft. The coils of the motor-magnet are wound on 
bobbins which are slipped over the cores; it is therefore easy 
to change a coil or to replace it for any purpose whatever. 

The field is wound in shunt to the armature, and is rela¬ 
tively of a very high resistance. 

This reduces the amount of electrical energy required to en¬ 
ergize the field magnet to a very small fraction of the total 
electrical energy absorbed by the motor. The armature bore 

is thoroughly well built arid is a very solid and substantial 

structure. 

At the same time the perfect lamination of the core reduces 

the loss by Foucault currents to a small amount. 

The winding on the armature, which is a modification of 

the well-known Siemens’ type, is of very low resistance. 

The copper wire on the armature is held in place by means 
of bands, which are made of such strength that it is impossi¬ 
ble for them to yield from the centrifugal force, even when the 
motors are run at abnormal speed. 

The Perret Motor .—The chief distinctive feature of this 
machine is the lamination of the field magnet. Instead of 

casting or forging this in several solid pieces, as is usually 

done, it is built of thin plates of soft charcoal iron, which are 

stamped directly to their finished form and clamped together by 


282 


DYNAMO-ELECTRIC MACHINERY. 


bolts in such a manner as to secure great mechanical strength. 

The advantages of such a construction are, in brief, a 
magnetic field of great intensity and the entire prevention of all 
wasteful induced currents in magnets and pole-pieces. 

The armature core is also laminated, and the plates have 



THE PERRET MOTOR. 


teeth, which form longitudinal channels on its periphery, in 
which the coils are wound. 

The plates in both field and armature are in the same 
plane, and are of soft charcoal iron, with its grain running in the 
direction of the line of magnetic force, and there is the least pos¬ 
sible break in the continuity of the circuit, there being no air gap 
between the iron of the field and the iron teeth of the armature, 
except that required for clearance in rotation. Thus we have a. 

































































































COMMERCIAL STATIONARY MOTORS. 


283 


magnetic circuit of lowest possible resistance, and it follows from 
well known laws that we secure the maximum of effective magnet- 
ism with a minimum expenditure of magnetizing power. 

The armature coils being practically imbedded in the armature 
receive the highest inductive effect from the intensely magnetized 
iron. 

The high efficiency which such construction should give theo¬ 
retically is practically demonstrated by the machines in actual 
work, and ranges from 7o per cent, in the smaller to 93 per 
cent in the larger. 

Attempts have been made by many since the days of 
Pacinotti to use toothed armatures, but with the result that very 
troublesome and wasteful heating effects were produced in the 
solid magnets and pole pieces commonly used. With laminated field 
magnets these disadvantages are avoided, and we are able to secure 
the advantages enumerated, as well as others, among which may be 
mentioned the important ones, positive driving of the armature coils 
and less liability of winding out of balance. 

It will be seen that the armature is a ring of compara¬ 

tively large diameter, with longitudinal channels on its periphery, 
in which the conductors are wound, and thus imbedded in the 
iron, which is in such close proximity to the iron pole pieces 

that there is practically no gap in the magnetic circuit. 

The field consists of three separate magnets arranged at 
equal distances around the armature, each magnet having two 

pole pieces. See Figure 160. The winding is such as to 

produce alternate North and South poles. The magnets aie 
built up of plates of soft charcoal iron, which aie shaped as 
shown in the diagram, and the magnet thus produced is of such 
a form that it may be readily wound in a lathe. A non- 


2S4 


DYNAMO-ELECTRIC MACHINERY. 


magnetic bolt passes through a hole in each pole piece and the 
plates are clamped together between washers and nuts on the 

same. These bolts also serve to attach the magnets to the 

# 

two iron end frames, which are of ring shape and are bolted 
to the bed plates of the machine. 

The magnetic circuit is of unusually low resistance by rea- 



figure 160. 


son of its shape, its shortness, which is shown by the diagram, 
and the superior quality of iron used. 

There is no magnetism whatever in the frame, bed or shaft 
of the machine, as the magnets are supported at some distance 
from the frame by means of the non-magnetic bolts, and the 
armature is mounted on the shaft by spiders of non-magnetic 
metal. 

There is therefore no opportunity for magnetic leakage, and 








COMMERCIAL STATIONARY MOTORS. 


2S5 


fuitheimoie, the whole is enclosed by a shield or case of sheet 
metal, as shown in the illustration. 

The practical advantages of low speed machines are many. 
F01 instance in ordinary machine shops, wood-work shops, print- 
ing offices, etc., the shaft is commonly run 200 to 300 revolutions 
per minute, and it is a simple matter to belt direct to it from a 
motor running 5^° to 600 revolutions, thus saving the first cost of 
a countershaft and one belt, and saving, also, considerable power 
which would be lost in transmitting through the countershaft and 
additional belt, which would be used necessarily with a motor of 
high speed. The advantage is equally as great in case of eleva¬ 
tors operated by a belt from the motor, and indeed, it is possible 
to gear direct from the motor to the elevator. 

The Excelsior Motor. The engraving presented illustrates the 
arc light circuit or constant current motor of the Excelsior Elec¬ 
tric Co. This motor has its armature and field magnet coils con¬ 
nected in series. As it is supplied with current by a generator 
whose electromotive force is varied by an automatic regulator to 
suit the demands of the motors on its circuit, it would run at 
a constantly increasing speed, when lightly loaded, were it not 
regulated and the speed kept uniform by a governing device. This 
consists of a centrifugal governor which controls the strength of the 
field magnets by cutting out the successive layers of wire in the 
coils as the load decreases, and cutting them in when it increases. 

The two main bearings of the motor shaft and the ball and 
socket bearings of the governor are provided with oil chambers, 
from which the oil is led to the wearing surfaces by means of felt 
strips. 

Tesla Polyphase Motor , j H.-P.(Rotating field type ). The 
upper photograph, page 287, illustrates a 5-horse-power 1 esla motor, 


2.S6 


DYNAMO-ELECTRIC MACHINERY 



THE EXCELSIOR MOTOR. 






































































































































































































































































COMMERCIAL STATIONARY MOTORS 



TESLA ROLY PHASE MATOK 


DISMANTLED 















288 


DYNAMO-ELECTRIC MACHINERY. 


of the rotary field type, complete, while the lower photograph 
shows the same motor dismantled. It will be noted that the 
construction is such as to entirely conceal and protect against 
mechanical injury the coils of both field and armature. Neither 
commutator nor collector is used. In the Tesla motors of the 
two-phase type the winding of the field is made up of two 
distinct electrical circuits. The currents traversing these circuits 
differ in their phase; that is to say, the maximum strength of 
one current occurs at the time when the other current is a 
minimum, the result being rotation of the magnetism of the 
field. The armature is short circuited, and the currents traversing 
it are simply the low potential currents induced by the field. 
The insulation of the armature is not at any point subjected to 
a potential exceeding a very few volts, and it is, therefore, 
practically impossible to burn out this armature, while the ma¬ 
chine may be safely operated in places so exposed to moisture 
as to make the use of direct current machinery impracticable. 
The construction of the field admits of very high insulation, and 
circuits carrying comparatively high potentials may be connected 
to it without the interposition of step-down transformers. 

The starting motors used in connection with the two-wire 
synchronous system are of this general type, the necessary differ¬ 
ence of phase being obtained by special methods of winding 
the field circuits. 



COMMERCIAL RAILWAY MOTORS. 


289 


CHAPTER XVII. 

TYPES OF COMMERCIAL RAILWAY MOTORS. 

I N the construction of the electric motor for car propulsion, the 
motor acts simply for the transformation of electrical energy with 
mechanical energy. A current of electricity is sent through the 
armature and field magnets of a motor which causes the armature 
to revolve. Formerly fast speed motors were used in electric rail¬ 
way service, in which the armature revolved with great rapidity, 
necessitating the use of numerous gears and pinions by which the 
motion was communicated to the axle of the car. At present, slow 
speed motors are almost wholly used, by which the intermediate 
gears and pinions are left out, there being only one gear and pin¬ 
ion, the gear being upon the axle of the car and the pinion upon the 
shaft of the motor. There are, however, some exceptions to the 
rule. These exceptions are in gearless motors, particulars of which 
will be given later in this chapter. We will now call attention 
to the different styles of railway motors. 

The Thomson-Houston W. P, Railway Motor, The accom¬ 
panying illustration gives an excellent idea of this motor, which 
is manufactured by the General Electric Company. 

The new machine embodies some decidedly novel features and its 
performance on the special car equipped with it was very favorably 


290 


DYNAMO-ELECTRIC MACHINERY. 


commented upon. It is known to the trade as the W. P. motor, 
which being interpreted, means water-proof, and it well deserves the 
name, because of the particularly complete iron-clad character of 
the field magnets. 

The figure gives a perspective view of the motor, and from it 
the arrangement of the iron is at once obvious. Singularly enough, 
it is a two-pole machine so arranged on the theory that the com- 



THE TIIOMSON-HOUSTON W. P. RAILWAY MOTOR. 

paratively slight gain in the weight efficiency that could be obtained 
with a multipolar type is more than offset by the increased com¬ 
plication of the windings. The only portions of the machine open 
to the outside air are exposed at the two oval openings at the ends 
of the armature shaft, and even these can be easily fitted with 
covers should such a course prove desirable. The whole magnetic 
circuit is composed of two castings bolted together and free to 



































































COMMERCIAL RAILWAY MOTORS. 


29I 


swing apart by a hinge allowing ready access to the armature. 
The armature itself is nearly twenty inches in diameter, a very 
powerful Pacinotti-ring nearly six inches on the face and of about 
the same depth. It is wound with comparatively coarse wire in 
sixty-four sections, with fourteen turns to the section. Each coil is 
tightly placed in the space between two of the projecting teeth, and 
about the interior space the separate coils are closely packed, leav¬ 
ing only sufficient room for the four armed driving spider. 

As will be seen, the armature takes up most of the full height 
of the machine, the pole pieces being but trifling projections, and the 
requisite cross section of iron being obtained by extending the poles to 
form a closely fitting iron box that appears in the exterior view. 

The General Electric Company's 54. Railway Motor. —The rapid 
growth of passenger traffic resulting in the increasing use of heavy 
cars on the lines of many of the electric roads operating within city 
limits has induced the General Electric Company to design and 
manufacture a motor known as the GE-54. 

It is adapted for use on a minimum gauge of 48!" and in gen¬ 
eral design and construction is similar to the GE-52. 

Rating. —On 500 volt circuits the GE-54 railway motor with 
three-turn armature will develop 25 H. P. The output is based on 
the standard rating; that is, a maximum rise of 75 0 C. in the tem¬ 
perature of this winding after a run of one hour at full rated load, 
the temperature of the surrounding air not exceeding 25 0 C. 

Mag?iet Frame. —The magnet frame is in the form of a hex¬ 
agon with well rounded corners, and is cast in two pieces of soft 
steel of high magnetic permeability. The two castings are bolted 
together, but the front bolts are hinged in order that the lower 
frame may be swung down conveniently so as to permit inspection or 
repairs of the field or armature. 

There is an opening in the frame just over the commutator 
large enough to provide for the removal of the brush holders 
and brush holder yoke and also to permit of inspection of the 
commutator and brush holders. The cover, which is of malleable 
iron, is held in place by an adjustable cam locking device, and 
can be readily removed when necessary. The lower frame has a 
small opening directly under the commutator, also protected by a 
suitable cover. 

Pole Pieces and Field Coils. —The pole pieces are built up from 
thin soft iron laminations, riveted together, and bolted to the 
frame by through bolts with nuts on the outside. 


29 2 


DYNAMO-ELECTRIC MOTOR 



LOWER FRAME DROPPED-SHOWING ARMATURE READY FOR REMOVAL, 



































COMMERCIAL RAILWAY MOTORS. 


2 93 


The four field coils are placed at an angle of 45 0 from 
the horizontal, and are held in place by pressed steel flanges 
or spool holders which are clamped to the pole pieces. The 
coils are made of asbestos, cotton covered wire, and are further 
insulated with wrappings of varnished cloth and tape. The insu¬ 
lation on the coils is subjected to a high potential test of 4000 
volts alternating current. 

Armature .— The armature is of the ironclad type, and the 
core is built up of thin soft iron laminations which are care¬ 
fully japanned and securely keyed to the shaft. The laminations 
are clamped at each end by cast-iron heads which are also keyed 
to the shaft. The core is hollow, and is ventilated by the air 
which enters the pinion end of the core, and passes out through 
the air ducts placed at regular intervals among the laminations. 

The armature winding is of the series drum type, the num¬ 
ber of turns per coil varying with the requirements of each case. 
The coils are made up in sets; and, before being placed in the 
slots of the armature core, each set is formed, and thoroughly 
insulated with specially prepared tape and cloth which have high 
insulating qualities and are practically impervious to moisture. 

The terminals of each coil are brought directly to the com¬ 
mutator segments, and soldered so as to properly connect the 

coils to each other and' at the same time form the connections 
between the windings and the commutator. 

The Westinghouse Four-pole Single-Reduction Street Railway 
Motor . — A view of the motor is shown on page 294, bringing 
out more prominently the gear casing. T he construction of the 
motor can be readily comprehended by referring to the. view. 
Here are shown the castings complete of the motor, consisting of 
only three parts — the frame and the two semi-cylinders, the two 
latter being practically one. T he size of the frame is such that 
it can be placed upon a bogie-truck, being equally well adapted 
for an eight-wheel as for a four-wheel car. The width of the 

motor is such that it can be used on a 3 feet 6 inch gauge. 

In the sides of the two semi-cylinders are seen the holes where 
the plates are secured, which serve as a protection to the sides 

of the machine. . 

If it is necessary, the machine can be entirely shut in. 

It was formerly believed that a motor could not be thus 
enclosed, since it needed ventilation; but experience with slow 
speed motors has demonstrated that if a motor has been correctly 


D\NAMO-ELECTRIC machinery 







% 


2 94 





RAILWAY MOTOR. 














































































COMMERCIAL RAILWAY MOTORS. 


2 95 

designed, electrically and mechanically, and properly constructed, 
there is no difficulty whatever in enclosing it. At the same 
time, if, in some cases, it be deemed advisable to allow a 
small opening for ventilation, the plates can be constructed ac¬ 
cordingly. 

This method of enclosing the motor is exceedingly conven¬ 
ient in rain and snow storms, and especially where the cars pass 
over trestles which expose the motor. Heretofore, considerable 
trouble has been experienced from water dripping on the motor 
through the car floor. In this motor, as is obvious, such troubles 
are eliminated. Again, the objections to a motor being exposed 
to water, dirt and dust, can be appreciated when it is remem¬ 
bered that a large number of engineers favor some method of 
mounting the motor on the car floor. The above objections are 
overcome by making the motor ironclad. By again referring to 
the view there will be seen the four internal poles; hence it is 
called a four-pole motor. Some of the advantages of a four-pole 
motor over a two-pole machine, are: slower speed; great sim¬ 
plicity ; more symmetrical; and a greater radiating surface for 
the field coils. In case a two-pole motor is used, and the same 
amount of wire is wound about these two poles, the radiating 
surface is far less than where there are four poles. 

Another important feature to be noticed is the form of the 

motor proper; namely, circular. It is a well known law in 

mechanics that the strongest form is the arch; consequently, by 

this cylindrical form, we obtain the maximum strength with the 

minimum amount of material. All corners and sharp edges which 
mean unnecessary weight, and at the same time having a ten¬ 
dency to reduce the efficiency, are eliminated from this machine. 
The fields are enclosed and protected, not merely externally by 























































































































































































































































































COMMERCIAL RAILWAY MOTORS. 


2 97 


the surrounding cylindrical shell, but also internally by a heavy 
brass cap. There is no liability to accident in case they strike 
any obstruction in the road, neither can they be injured by gross 
carelessness in handling. 

The cast iron frame on which the motor is mounted, forms 
a distinguishing feature of the Westinghouse machine. The frame 
is rectangular, in one casting, and made strong at points subjected 
to the greatest strains. Special machinery has been devised for 
boring out the holes for bushings, so that the frame, and, in 

fact, all parts of the motor, are interchangeable. By means of 

this frame the armature shaft and car axle are maintained in 

alignment, and consequently perfect meshing of the gears is 

obtained, which experience has proved to be of importance. 



figure 162. 


The gearing is mounted closely to the frame, so as to avoid 
the objectionable buckling and tendency to loosen the moving 
parts. This method gives a strong mounting and perfect rigidity 
between the parts of the motor. Moreover, by extending this 
frame around the motor and suspending it at both corners, we 
distribute the strains and prevent the abnormal wearing of the 
bearings, so characteristic of center suspension. 

The illustration, see Figure 161, shows the method of hinging 
the field castings. These, as will be noticed, can be swung 
back, giving easy access to the fields and armatuie. It will be 
observed that the poles protrude radially from the interior of the 














298 


DYNAMO-ELECTRIC MACHINERY: 


cylindrical shell. The field coils, one of which is shown in 
Figure 162, are slipped over these poles, held in position and 
at the same time protected from the interior by a brass cap. 
The ease with which the fields can be removed or replaced 
needs but a glance to be understood. Any field can be removed 
without disturbing any other part of the motor, and this can be 
accomplished in little time. The lower fields can be similarly 
changed by swinging back the lower semi-cylinder. The arma¬ 
ture is then ready to be taken out, and by taking off the brush¬ 
ing cap and placing a sling about the armature, it can be lowered 
into the pit without obstruction or danger of injuring the same. 



FIGURE 163. 

The armature is what is known as the drum type, which 
experience has demonstrated to be superior to other types for 
street railway work. The armature core is built up of lamina¬ 
ted grooved iron plates, so that the completed core has slots to 
receive the wires. In the armature the wires are imbedded in 
iron, hence they cannot be injured from ordinary external causes. 
Since the surface of the armature is iron, the air space, that is, 
the distance between the iron of the armature and the pole pieces 
is reduced to a minimum, increasing the efficiency of the motor. 

The armature shaft is manufactured from the best grade of 












COMMERCIAL RAILWAY MOTORS. 


2 99 

foiged steel, especially prepared for this purpose. The construc¬ 
tion of the shaft and armature make it exceedingly strong, and 
capable of w ithstanding the severe strains sometimes brought upon 
it. In looking at the frame, it will be noticed that the oil re¬ 
ceptacles are sunk into the same. These oil receptacles are so 
placed that there is no possibility of injuring them. It is worthy 
of attention that these facilities for oiling are excellent. The oil 
boxes are large, and the method of oiling is the same as that 
of the high speed motor, with which they have never had a hot 
box, so that it can be said with confidence no trouble will be 
experienced from this source with their slow speed motor. 

The field coils are wound with* wire having exceedinglv large 
carrying capacity. The arrangement adopted for the brush holder 
see Figure 163, has also been carefully worked out. It consists of a 
square oak holder attached to the side of the frame, and carry¬ 
ing the brush-holders proper, which are clamped so that they 
can readily be adjusted. The carbon brushes are placed in a 
sliding frame, and pressed against the commutator by a pair of 
springs, which can be released by a pressure of the finger, and 
the carbon slipped out for replacement when worn. The casting- 
supporting the brush holder is fastened to the bottom of the motor 
frame, so that the brushes rest on the upper part of the com¬ 
mutator, the greater part of which is exposed above so that the 
commutator can be cleaned from the inside as well as from the 
outside of the car. 

The Short Gearless JSIotor. The gearless motor (designed 
by the Short Company) is shown on page 300. Referring to the 
machine in a general way, it is seen that all gearing is absolutely elim¬ 
inated, the number of bearings is reduced to two on each motor 
and four in the equipment. The armature speed comes down to 


























COMMERCIAL RAILWAY MOTORS. 


3 01 


the minimum, namely, that of the car axles in practical opera¬ 

tion. The noise of gearing and brushes is entirely obviated, and 
there are but three wearing parts on each motor. The intensity 
of the magnetic field is now at its maximum; this effect being 
due, not to a material increase in the weight of armature and 

pole pieces, but to the wholly different method of construction, 
Instead of two magnets we find eight; instead of a wide mag¬ 
netic gap, we find one extremely narrow, with consequently 
great intensity of the “field of force.” Instead of a drum arm¬ 
ature of small diameter, we find a ring armature of compara¬ 

tively large diameter, and increased “leverage;” the sum total 
beins: that we have here in full measure a motor of the second 

type, namely, one with an armature revolving at low speed in 

an intense “magnetic field,” exerting a power fully equal to the 
motor with gearing, and at a considerable less expenditure of 
current since all friction of gearing is eliminated. 

The motor is complete in itself. It is not keyed to the car 
axle, nor does it touch at any point. The motor as a whole can 
be taken off the car axle after removing a wheel, but in practice 
it will rarely or never be found necessary to do this. A plan 

of the 15 horse power gearless motor is shown in Figure 164. 
A sectional view is shown in Figure 165. 

The field magnets are eight in number, four on each side 

of the armature. They face each other at a distance of only 
ten inches and thus form a most intense magnetic field. The 
magnets are bolted to the framework of the motor, in the cen¬ 
ter of which are the bearings which carry the hollow armature 
shaft. (See Figure 166.) The double arms running out from 
the framework to the cross girders on the truck make provision 
for the support of the entire motor. The insulation between 


3°2 


DYNAMO-ELECTRIC MACHINERY. 



FIGURE 164 














































































































































































COMMERCIAL RAILWAY MOTORS. 


303 


these bitickets and the gilders is provided by means of heavy 
rubbei bushings through which pass the bolts. By removing 
the bolts attaching the fields to the supporting framework, the 
coils may be quickly taken out, either for repair or to more 
easily get at the armature. 

The armature is keyed to a hollow steel shaft, which is 
concentric with the axle of the truck, an inside clearance of one 
inch all around being provided for. The armature proper con¬ 
sists of a laminated iron core upon which are mounted separate 
and entirely independent coils, following the well-known 
methods of the Short double reduction type of motor. These 
coils are perfectly ventilated, and in past practice almost no 
trouble has been experienced from burn-outs. It is the one 
street car armature at present constructed of which it can be 
truly said that the coils are absolutely Independent , and can be 
separately rewound in case of accident, at almost nominal ex¬ 
pense. Mounted upon the hollow shaft, close to the armature, 
is the commutator, which is protected from injury by the sur¬ 
rounding pole pieces. The commutator is massive in construc¬ 
tion and of large diameter, the idea being that, because of its 
massiveness and slow speed, the wear will be reduced to a 
minimum, and the replacing of the commutator will occur only 
at long intervals. On the ends of the hollow shaft are mount¬ 
ed two discs fastened thereto, the peripheries of which are insu¬ 
lated from the hubs by the special wooden web construction. 
Between the commutator and the disc on the one side and the 
armature and the second disc on the other, are the bearings, 
which are carried by the motor frame. 

It has been before said that the motor has no connection 
whatever with the car axles; it follows, therefore, that it is nec- 



































































































































































































COMMERCIAL RAILWAY MOTORS. 


3 °5 

essary to provide means of propelling the car by making some 
attachment between the hollow armature shaft and the wheels. 
This is done very simply by means of heavy coiled springs, 
which extend from the peripheries of the armature shaft discs 
to bosses on the wheels. Position and attachment of these springs 
are shown in Figure 167. They are of great strength, and can 
pull a very heavy weight with but slight extension or compres¬ 



sion. As they are attached to both disc and wheel upon circles 
of the same radius, their effort is a nearly direct circumferential 

pull. 

From the description above it is at once apparent that the 
entire motor is absolutely insulated from the truck at every point. 
This is a feature which we believe to be of great importance. By 
this means leakage or accidental connection between field or ar¬ 
mature circuits and the iron frame work (which may be caused 
by moisture, dust, dirt, etc.), does not produce a “ground circuit,” 































































3°6 


DYNAMO-ELECTRIC MACHINERY. 


and consequent burn-out of field or armature coil, as is the case 
with other types of machines. 

To protect the motor from dust, moisture, etc., which have been 
a potent source of trouble in other forms of equipment, an iron 
case completely encloses the motor, except at the top, where 
necessary ventilation is provided, and is water-tight up to the 
axles. To get at the motor, it is only necessary to unlatch one end 
of the casing and swing it down and out away from the mechanism. 



FIGURE 167. 


The dimensions of the motor are as follows: From the cen¬ 
ter of the axle to the bottom of the casing is i2| inches. On a 
36-inch wheel which we strongly advise, not only in the gear¬ 
less, but in other types of motor, there is thus a clearance of 
^ inches which is ample for all purposes. At a speed of ten 
miles an hour, the armature revolves at 94 revolutions per min¬ 
ute, with a 36-inch wheel. The equivalent speed of the single 
reduction motor would be at least 400, and of a double reduction 
motor about 1,200. One of the most valuable features of the 












COMMERCIAL RAILWAY MOTORS. 


3°7 

machine is the facility with which it can be repaired in case of 
necessity. By loosening four bolts in the motor framework, and 
by taking oh the iron strips below the wheel boxes, one end of 
the car may be jacked up, and the axle wheels and armature com¬ 
plete run out from under, into the light of day. The armature 
coils may be rewound without removing the armature from the 
car axle. Field coils can be repaired as easily. The commuta¬ 
tor may be reached and dressed while the machine is running. If 
steel tired wheels are used by a special arrangement the motor may 
be jacked up, raising the wheels from the ground, current brought 
to the motor, and the wheels turned just as would be the case 
on the truck, so that by a special “tool-jig” the wheels may be 
turned down as required, thus removing any flat spots dr imper¬ 
fections. Or the wheels and axles may be turned from outside 
through the hollow shaft of armature, without the least effect on 
motor, it being, of course, necessary, however, to remove the 
spring attachment between the hollow shaft discs and the wheels. 
In case it is found necessary to replace a commutator, a wheel 
must be pressed off and the commutator remoyed bodily. This 
could be done only with great difficulty if the armature were 
keyed directly to the axle instead of being on the hollow shaft. 
The commutator will have a life three or four times that of the 
wheels in common use on electric railways, and it will not 
usually be necessary to press oft' a wheel for the express purpose 
of replacing a commutator. 


DYNAMO-ELECTRIC MACHINERY. 


3°S 


APPENDIX A. 

MANAGEMENT OF DYNAMOS AND MOTORS. 

Locatioji .—Proper care and good management are necessary 
for the success of any dynamo or motor. Cleanliness is ot 
great importance; much trouble is caused by its neglect. A 

dynamo or motor should be firmly set on a solid foundation: 

this is especially important with large machines, for if the foun¬ 
dation is poor, the vibrations caused by the rotation of the 
armature may damage the machine in many ways. The iron 
base of a dynamo or motor should always be insulated from 

the foundation to prevent a ground. A dynamo or motor 

should always be located in a dry place. Especially avoid a 
location near where grinding, filing or turning is being done, as 
the filings, chips or dust from such work, may fly on the ma¬ 
chine and injure the armature or commutator. Also in select¬ 
ing the location, leave room enough to inspect and make any 
necessary repairs to the machine or to remove the armature. 

Stai'thig the Dynamo .—First make sure that the machine 
is perfectly clean; that no screws or parts are loose; that all 
bearings are properly oiled and that the oil cups have a suffi¬ 
cient supply of oil in them; the brushes set at the proper 
point and the circuit left open. Now start the dynamo with 
care and gradually bring it to full speed. If anything appears 




MANAGEMENT OF DYNAMOS AND MOTORS. 


3°9 

to be wrong shut the machine down instantly, find and remedy 
the trouble before starting again. 

Starting" JMotors .—The same care must be observed in 
starting motors as that' used with dynamos. The operation is 
simple as it only consists in operating a switch. Both a switch 
and a rheostat is generally used for starting and stopping 
“shunt” or compound wound motors. The use of a rheostat 

is for taking care of the current in the armature, the resistance 

! 

of the armature being very low in order to get high efficiency 
and constant speed, and the quantity of current going through 
it in starting might be a great many times more than its nor¬ 
mal numbers of amperes, hence this “resistance” or rheostat is 
interposed, in the external circuit, between the motor and switch. 

Dynamo Fails to Generate .—This trouble may arise from 
a number of causes; it may be located in the machine or in 
the external circuit. If in the machine it may be caused by 
a short circuit in the armature or pole pieces, if so the trou¬ 
ble must be located and the armature or pole piece rewound. 

It may be caused by a poor connection or broken wire in 

the machine, or by the brushes not being in contact with the 

commutator. Another cause is residual magnetism too weak or 

destroyed, due to proximity to another dynamo, or a jar to the 
machine. The remedy is to remagnetize the pole pieces by 
sending a current through the field coils from a battery or an¬ 
other dynamo. If this fails, reverse the direction of the cm- 
rent, as the trouble may be caused by the magnets having 
enough polarity to prevent the current building them up when 
sent in the direction first tried. Anothei cause is, not ha\ing 
the brushes in proper position. It the trouble is outside the 
machine it may be caused by an open ciicuit, /.<?., an open 


310 


DYNAMO-ELECTRIC MACHINERY. 


switch, a burnt out fuse, a broken wire or brushes not touch¬ 
ing commutator; look after these things carefully. 

Sparking at Commutator. —Too much sparking at the com¬ 
mutator may be due to: Brushes not set at the neutral point, 
by the machine being overloaded, by a rough commutator, by 
a short circuit, a broken circuit, a ground in the armature, or 

by brushes in poor contact with commutator. Examine the 

machine carefully, find the cause, and remedy it accordingly. 
A brush should never be lifted from the commutator while the 
machine is, running; it will cause an arc and make a bad spot 
on the commutator. Only a gentle pressure of the brushes on 
the commutator is required; the brush holder springs should al¬ 
low a certain amount of flexibility in order to prevent sparking. 

Bad Commutators. —The commutator is one of the most 
sensitive parts of the dynamo or motor; it should always be 
kept smooth. When a commutator gets rough it may be made 
smooth by the use of emery cloth, or fine sand paper. Either 
of these may be wrapped around a block of wood and pressed 
against the commutator, taking care to raise the brushes before 
the operation; it should never be done while the dynamo is at 

work. Great care must be taken to clean off any sand or 

emery dust that may remain upon the commutator, brushes or 
shaft, as it will cut the surface of them for a long time, and 
might cause serious damage. For spots and grooves on commu¬ 
tator there is no remedy but turning in the lathe. Files should 
never be used; it is quite impossible to produce a true cylinder 
with them. 

Hints for Running Dynamos and Motors. — Keep iron and 
steel tools away from the machine while running and never file 
near it. Iron and steel tools and filings are liable to be drawn 



MANAGEMENT OF DYNAMOS AND MOTORS. 


3 11 

by the magnetism into the machine and damage it. For this rea¬ 
son use brass or zinc oil cans for lubricating. Do not spill oil or 
water upon a dynamo, and have shields to prevent adjacent ma¬ 
chinery from spattering oil upon it. Have a pair of bellows to 
blow the dust from the commutator and armature coils of the 
machine. Oil is an insulator, therefore very little of it should 
be used upon the commutator; a few drops rubbed on with the 
.hand is sufficient. For the sake of personal safety it is a good 
plan to wear rubber boots and thick rubber gloves when at work 
around circuits of 500 volts and upwards. Rubber covers' are 
now made for the handles of all iron and steel tools which every 
electrician should use. Touch the bearings and field-coils occa¬ 
sionally to see if they are hot. To ascertain if the armature is 
heated, place the hand in the current of air thrown out from the ma¬ 
chine by its centrifugal force. Be careful and not overload the 
machine, as more troubles arise from this than any other cause. 

Conclusion .—The author has not attempted to point out all 
the troubles and their remedies to which the dynamo or motor 
is heir, but thinks he has shown a sufficient number to give the 
reader a fair understanding of how to successfully manage small 
machines. For further information upon the subject, we would lefer 
the reader to the excellent work “Practical Management of Dy¬ 
namos and Motors,” by Crocker & Wheelei. 


DYNAMO-ELECTRIC MACHINERY, 


APPENDIX B. 

TABLE SHOWING THE DIFFERENCE BETWEEN WIRE GAUGES. 


New Brown & 


No. 
0000 . 

• 

• 

e 

British. 
.400 . 


0 • 

London. 
.454 . 

• 



Stubs'. 
.454 . 

• • 


Sharpe's. 

.460 

000 





.372 . 



.425 . 




.425 . 



.40964 

00 





.348 . 



.380 . 




.380 . 



.36480 

0 . 





.324 . 



.340 . 




.340 . 



.32495 

1 . 





.300 . 



.300 . 




.300 . 



.28930 

2 . 





.276 . 



.284 . 




.284 . 



.25763 

3 





.252 . 



.259 . 




.259 . 



.22942 

4 . 





.232 . 



.238 . 




.238 . 



.20431 

5 . 





.212 . 



.220 . 




.220 . 



.18194 

6 . 





.193 . 



.203 . 




.203 . 



.16202 

7 . 





.176 . 



.180 . 




.180 . 



.14428 

8 . 





.160 . 



.165 . 




.165 . 



.12849 

9 . 





.144 . 



.148 . 




.148 . 



.11443 

10 . 





.128 . 



.134 




.134 . 



.10189 

11 . 




o 

.116 . 



.120 . 




.120 . 



.09074 

12 . 





.101 . 



.109 . 




.109 . 



.08081 

13 . 





.092 . 



.095 . 




.095 . 



.07196 

14 . 





.080 . 



.083 . 




.083 . 



.06408 

15 . 





.072 . 



.072 . 




.072 . 



.05706 

16 . 





.064 . 



.065 . 




.065 . 



.05082 

17 . 





.056 . 



.058 . 




.058 . 



.04525 

18 . 





.048 . 



.049 . 




.049 . 



.04030 

i9 . 





.040 . 



.040 . 




.042 . 



.03589 

20 . 



o 


.036 . 



.035 . 




.035 . 



.03196 

21 . 





.032 . 



.0315 




.032 . 



.02846 

22 . 





.028 . 



.0295 




.028 . 



.025347 

23 . 





.024 . 



.027 . 




.025 . 



.022571 

24 . 





.022 . 



.025 . 




.022 . 



.0201 

25 . 




o 

.020 . 



.023 . 




.023 . 



.0179 

26 . 





.018 . 



.0105 




.018 . 



.01594 

27 . 





.0164 



.01875 




.016 . 



.014195 

28 . 





.0148 



.0165 




.014 . 



.012641 

29 . 

o 

o 



.0136 



.0155 




.013 . 



.011257 

30 . 





.0124 



.01375 




.012 . 



.010025 

31 . 





.0116 



.01225 




.010 . 



.008928 

32 . 


o 



.0108 



.01125 




.009 . 



.00795 

33 . 





.0100 



.01025 




.008 . 



.00708 

34 . 





.0092 



.0095 




.007 . 



.0063 

35 . 

o 


• 


.0084 



.009 . 


• 


.005 . 



.00561 

36 . 

• 


0 

« 

.0075 


• • 

.0075 

• 

• 

9 

.004 . 



.005 
















USEFUL TABLES 


3 1 


Table of Different Ganges, with tbeir Diameters and Areas in Mils. 


STANDARD. 


No of 
Gauge. 

Diameter 
Id .Mila. 

Area In 
CM=d» 

7-0 

600 

260000 

6-0 

464 

216296 

6-0 

432 

186824 

4-0 ' 

400 

160000 

3-0 

372 

138384 

2-0 

348 

121104 

0 

324 

104976 

1 

300 

90000 

2 

276 

76176 

3 

262 

63604 

4 

232 

63824 

6 

212 

44944 

6 

192 

36864 

7 

176 

30976 

8 

160 

26600 

9 

141 

20736 

10 

128 

16384 


AMERICAN. 


No. of 
Gauge. 

Diameter 
Id Mils. 

Area in 

CM=d2 

4-0 

4600 

211600 

3-0 

4096 

167805 

2-0 

3648 

133079 

0 

3219 

106592 

1 

2893 

83694 

2 

2576 

66373 

3 

2294 

62634 

4 

2043 

41742 

6 

1819 

83x02 

6 

162 

26244 

7 

1443 

20822 

8 

1286 

16612 


BIRMINGHAM. 


No. Of 
Gauge. 

Diameter 
in Mils 

Area in 
C M=d* 

4-0 

454 

206116 

3-0 

426 

180625 

2-0 

380 

144400 

0 

340 

115600 

1 

300 

90000 

2 

284 

80656 

3 

269 

67081 

4 

238 

66644 

5 

220 

48400 

6 

203 

41‘209 

7 

180 

32400 

8 

165 

27225 

9 

148 

21904 

10 

134 

17966 


Table of Different Ganges, with their Diameters and Areas in Mils. 


STANDARD 

AMERICAN. 


BIRMINGHAM 

No. of 

Diameter 

Area in 

No. of 

Diameter 

Area in 


No. of 

Diameter 

Area tn 

Gauge. 

lu Mila. 

C M=d« 

Gauge. 

in Mile. 

CM=d! 


Gauge. 

in Mile. 

CM=d» 

11 

110 

13456 

9 

1144 

18110 


11 

120 

14400 

12 

104 

10816 

10 

1019 

10381 


12 

109 

11881 

13 

092 

8464 

11 

0907 

8226 


13 

095 

9025 

14 

080 

6400 

12 

0808 

6528 


14 

083 

6889 

15 

072 

6184 

13 

072 

6184 


15 

072 

5184 

16 

06t 

4096 

14 

0641 

4110 


16 

065 

4225 

17 

056 

8136 

15 

0571 

3260 


17 

068 

3364 

18 

048 

2304 

16 

0608 

2681 


18 

049 

2401 



17 

.0462 

2044 


19 

042 

1764 

19 

040 

1600 

18 

0403 

1624 




1225 

20 

036 

1296 

19 

0389 

1253 


20 

035 

21 

032 

1024 

20 

032 

1024 


21 

032 

1024 

22 

028 

784 

21 

0286 

820 


22 

028 

784 

23 

024 

576 

22 

0253 

626 


23 

025 

625 

24 

022 

484 

23 

0226 

610 


24 

022 

484 

25 

020 

400 

24 

0201 

404 


26 

020 

400 

26 

018 

324 

26 

0179 

320 


26 

018 

324 



























































DYNAMO-ELECTRIC MACHINERY, 


3 J 4 


Table of Dimensions and Resistances of Pure 

Copper Wire.* 

REVISED. 


No. 

B. & S. 

Diam. 

Mils. 

Area. 

Wgt & Length. Sp. gr. 8.9 

Circular 

Mils. 

Square 

Inches. 

Lbs. 

per 

1000 ft. 

Founds 

per 

mile. 

Feet 

per 

pound. 

0000 

460.000 

211600.0 

166190.2 

640.73 

3383.04 

1.56 

000 

409.640 

167805.0 

131793.7 

508.12 

2682.85 

1.97 

00 

364.800 

133079.0 

104520.0 

402.97 

2127.66 

2.48 

0 

324.950 

105592.5 

82932.2 

319.74 

1688.20 

3.13 

1 

289.300 

83694.5 

65733.5 

253.43 

1338.10 

3.95 

2 

257.630 

66373.2 

52129.4 

200.98 

1061.17 

4.98 

3 

229.420 

52633.5 

41338.3 

159.38 

841.50 

6.28 

4 

204.310 

41742.6 

32784.5 

126 40 

667.38 

7.91 

5 

181.940 

33102.2 

25998.4 

100.23 

529.23 

9.98 

6 

162.020 

26250.5 

20617.1 

79.49 

419.69 

12.58 

7 

144.280 

20816.7 

16349.4 

63.03 

332.82 

15.86 

8 

128.490 

16509.7 

12966.7 

49.99 

263.96 

20.00 

9 

114.430 

13094.2 

10284.2 

39.65 

209.35 

25.22 

10 

101.890 

10381.6 

8153.67 

31.44 

165.98 

31.81 

11 

90.742 

8234.11 

6467.06 

24.93 

131.65 

40.11 

12 

80.808 

6529.94 

5128.60 

19.77 

104.40 

50.58 

13 

71.961 

5178.39 

4067.09 

15.68 

82.792 

63.78 

14 

64.084 

4106.76 

3225.44 

12.44 

65.658 

80.42 

15 

57.068 

3256.76 

2557.85 

9.86 

52.069 

101.40 

16 

50.820 

2582.67 

2028.43 

7.82 

41.292 

127.87 

17 

45.257 

2048.20 

1608.65 

C.20 

32.746 

161.24 

18 

40.303 

1624.33 

1275.75 

4.92 

25.970 

203.31 

19 

35.890 

1288.09 

1011.66 

3.90 

20 594 

256.89 

20 

31.961 

1021.44 

802.24 

3.09 

16.331 

323.32 

21 

28.462 

810.09 

636.24 

2.45 

12.952 

407.67 

22 

25.347 

642.47 

504.60 

1.95 

10.272 

514.03 

23 

22.571 

509.45 

40112 

1.54 

8.1450 

648.25 

24 

20.100 

404.01 

317.31 

1.22 

6.4593 

817.43 

25 

17.900 

320.41 

251.65 

.97 

5.1227 

1030.71 

26 

15.940 

254.08 

199.56 

.77 

4.0623 

1299.77 

27 

14 195 

201.50 

158.26 

.61 

3.2215 

1638.97 

28 

12.641 

159.80 

125.50 

.48 

2.5548 

2066.71 

29 

11.257 

126.72 

99.526 

.38 

2.0260 

2606.13 

30 

10.025 

100.50 

78.933 

.30 

1.6068 

3286.04 

31 

8.928 

79.71 

62.603 

.24 

1.2744 

4143.18 

32 

7.950 

63.20 

49.639 

.19 

1.0105 

5225.26 

33 

7.080 

50.13 

39.369 

.15 

.8014 

6588.33 

34 

6.304 

39.74 

31.212 

.12 

.6354 

8310.17 

35 

5.614 

31.52 

24.753 

.10 

.5039 

10478.46 

36 

5.000 

25.00 

19.635 

.08 

.3997 

13209.98 

37 

4.453 

19.83 

15.574 

.06 

.3170 

16654.70 

38 

3.965 

15.72 

12.347 

.05 

.2513 

21006.60 

39 

3.531 

12.47 

9.7923 

.04 

.1993 

26427.83 

40 

3.144 

9.88 

7.7365 

.03 

.1580 

33410.05 


*1 mile pure copper wire 1-16 in. diam.=13.59 ohms at 15.5°C or 59.9°F, 






































































USEFUL TABLES 


3 J 5 


Table of Dimensions and Resistances of Pure 

Copper Wire.* 

REVISED. 


No. 


Resistance at 75°F 


lbs p. 1000 
ft. ins’d 

Feet per 
lb. ins’d 

B. 

R 

Ohms 

Feet 

Ohms 

& 

ohms per 

per 

per 

per 

H.B.&H. 

h.b.&h 

S. 

1000 feet. 

mile. 

ohm. 

pound. 

line wire. 

line wire. 

4-0 

.04904 

.25891 

20392.9 

.00007653 

800 

1.25 

3-0 

.06184 

.32649 

16172.1 

.00012169 

666 

1.50 

00 

.07797 

.41168 

12825.4 

.00019438 

500 

2.00 

0 

.09827 

.51885 

10176.4 

.00030734 

363 

2.75 

1 

.12398 

.65460 

8066.0 

.00048920 

313 

3.20 

2 

.15633 

.82543 

6396.7 

.00077784 

250 

4.00 

3 

.19714 

1.04090 

5072.5 

.0012370 

200 

5.00 

4 

.24858 

1.31248 

4022.9 

.0019666 

144 

6.9 

5 

.31346 

1.65507 

3190.2 

.0031273 

125 

8.0 

6 

.39528 

2.08706 

2529.9 

.0049728 

105 

9.5 

7 

.49845 

2.63184 

2006.2 

.0079078 

87 

11.5 

8 

.62849 

3.31843 

1591.1 

.0125719 

* 69 

14.5 

9 

.79242 

4.18400 

1262.0 

.0199853 


10 

.99948 

5.27726 

1000.5 

.0317946 

50 

20.0 

Ti 

1.2602 

6.65357 

793.56 

.0505413 



12 

1.5890 

8.39001 

629.32 

.0803641 

31 

32.0 

13 

2.0037 

10.5798 

499.06 

.127788 


14 

2.5266 

13.3405 

395.79 

.203180 

22 

45.0 ' 

15 

3.1860 

16.8223 

313.87 

.323079 


16 

4.0176 

21.2130 

248.90 

.513737 

14 

70.0 

17 

5.0660 

26.7485 

197.39 

.816839 


18 

6 3880 

33.7285 

156.54 

1.298764 

11 

90.0 

19 

8.0555 

42.5329 

124.14 

2.065312 


20 

10.1584 

53.6362 

98.44 

3.284374 



21 

12.8088 

67.6302 

78.07 

5.221775 



22 

16.1504 

85.2743 

61.92 

8.301819 



23 

20.3674 

107.540 

49.10 

13.20312 



24 

25.6830 

135.606 

38.94 

20.99405 



25 

32.3833 

170.984 

30.88 

33.37780 



26 

40.8377 

215.623 

24.4'J 

53.07946 



27 

51.4952 

271.895 

19.42 

84.39916 



28 

64.9344 

342.854 

15.40 

134.2 05 



29 

81.8827 

432.341 

12.21 

213.3973 



30 

103.245 

545.133 

9.686 

339.2673 



31 

130.176 

687.327 

7.682 

539.3404 



32 

164.174 

866.837 

6.091 

857.8498 



33 

207.000 

1092.96 

4.831 

1363.786 



34 

• 261.099 

1378.60 

3.830 

2169.776 



35 

329.225 

1738.31 

3.037 

3449.770 



36 

415.047 

2191.45 

2.409 

5482.766 



37 

523.278 

2762.91 

1.911 

8715.030 



38 

660.011 

3484.86 

1.515 

13864.51 



39 

832.228 

4394.16 

1.202 

22043.92 



40 

1049.718 

5542.51 

.9526 

35071.11 




*1 mile pure copper wire 1-16 in. diam.=13.59 ohms at 15.5°C. or 59.9°F. 













































































3 l6 


DYNAMO-ELECTRIC MACHINERY. 


TABLE OF ELECTRICAL UNITS. 


UNIT OF 

* NAME 

DERIVATION. 

sions in 
C. G. S. 
Units. 

Electromotive 

force. 

Volt. 

Ampere X Ohm . . 

IO 8 

Resistance. 

Ohm. 

Volt -5- Ampere . . 

IO 9 

Current. 

Ampere. 

Volt -f- Ohm . . . . 

IO 1 

Quantity. 

Coulomb. 

Ampere X Second 

IO 1 

Capacity. 

Farad. 

Coulomb -j- Volt . 

IO 9 
































USEFUL TABLES. 


3 J 7 


SIGNIFICATIONS 

OF SIGNS USED IN CALCULATIONS. 

= signifies equality, thus 5-[-2=7. 

+ signifies addition, thus 3-]-2=5. 

— signifies substraction, thus 8 — 6=2. 

X signifies multiplication, thus 5 X 3 = 15 - 

-f- signifies division, thus 18-5-3=6. 

: :: : signifies proportion, thus 2 is to 3— 

I I 

\ signifies square root thus \ 16=4. 
f/ signifies cube root thus 64=4. 

3 2 signifies 3 is to be squared 32=9. 

3 3 signifies 3 is to be cubed 33=27. 


3 l8 


DYNAMO-ELECTRIC MACHINERY. 


ELECTRICAL AND MAGNETIC UNITS. 

AMPERE. — The unit of current strength. It is the flow of 

electricity produced by the pressure of one volt on a resistance 
of one ohm. 

COULOMB. — The unit of electric quantity. It is the amount 
of electricity which flows past a given point in one second on 
a circuit conveying one ampere. 

FARAD. — The unit of capacity A condenser that will hold 
one coulomb at a pressure of one volt has a capacity of one 

farad. 

OHM. — The unit of electrical resistance. Ohm’s law states that 
the current in any circuit is equal to the E. v M. F. acting on 
it divided by its resistance. 

VOLT. — The unit of electro-motive force or pressure analogous to 
the head of water in hydraulics. 

WATT. — The unit of work. of a horse power, i. e. 746 

watts equal 1 horse power. We may find the watts used in a 

circuit by three formulae, thus: 

WATTS = Amperes (squared) X ohms. 

WATTS = Amperes X volts. 

WATTS = Volts (squared) -f- by ohms. 



USEFUL TABLES. 


3 r 9 

DYNE.—The absolute unit of force. It is that force which if 
it acts on one gramme for one second gives to it a velocity of 
one centimetre per second. In the *C. G. S. system the unit 
of magnetism is the force of a magnetic pole, which repels an 
equal pole at a distance of one centimetre with a force of one 
dyne. 


*C G S —The abbreviation o centimetre, gramme, second, and used to designate the 
so-called absolute system of measurement, viz.: The (Centimetre) the unit of length. 
The (Gramme) the unit of mass. The (Second) the unit ot time. 


3 2 ° 


- * 

DYNAMO-ELECTRIC MACHINERY. 


APPENDIX C. 

SOME PRACTICAL DIRECTIONS FOR ARMATURE WINDING. 

An armature of a dynamo may be defined as the part in 
which electricity is generated. Of the three inherent conditions 
involved in such a structure, mechanical, magnetic and electrical, 
the first two usually coincide; for the iron used to complete the 
magnetic circuit from pole to pole of the field, also supports 
and drives the wire in which the electricity flows. 

A Siemens “H” or shuttle armature is the simplest, and for 
small dynamos gives a much greater output than any other form. 
Such a core is shown in Figure 16S. It consists of a cast or 
wrought iron cylinder grooved deeply on both sides. For mount¬ 
ing it upon a shaft, an axial hole is drilled the entire length. 

Before winding such a core, the corners are to be rounded, 
and any roughness filed away. Amateurs are prone to pay too 
little attention to insulation. About three layers of tough and 
thin manilla paper should be shellacked on. Each layer should 
be allowed to become dry before putting on the next. The strips 
of paper should be cut differently for each layer, so that the 
joints will not come over each other, and in no case should a 
joint come over a corner of the core. Let the starting end of 
the wire be extra insulated with a few turns of tissue paper, 
well shellacked. Pass the wire along the groove, across the end, 
back in the other groove to the starting point; place a second 



ARMATURE WINDING. 


3 21 


turn along side the hist, and so on until one layer is complete. 
A little trial will show how to dodge by the shaft. Wind on 
other layers, pressing or hammering them tightly in place with 
a hard-wood stick, shellacking each in turn until the groove is 
completely hlled. The last layer may well have several coats 
of shellac. Figure 169 shows a section of wound core, with 
the wire exaggerated in size. The two ends of the wire are to 
be connected to a two-part commutator. 

Such an armature as this, 4 inches in length and 2 inches 
in diameter, with grooves i|x| inch is the kind used in a one- 
quarter-horse-power dynamo. Wound with f-pound double cotton 




FIGURE l68. FIGURE 169. 

covered No. 18 wire; about 200 turns can be put on, and the 
armature will give 35 volts and 6 amperes. On this as a basis, 
other potentials can be estimated. The electro-motive force will 
vary directly as the number of turns of wire; the products of the 
number of volts by the number of amperes; the watts will be 
constant, at about 200. For higher potentials it would be better 
to use two collector rings, and take the current alternating, as 
a two-segment commutator allows considerable sparking. 

Sometimes the center part of the core, over which the wire 
is wound, is made shorter than the crescent-shaped sides. 
The shaft is then not in the way of the winding. Brass 
caps, into which short lengths of shafting are driven, are screw- 


21 






3 23 


DYNAMO-ELECTRIC MACHINERY. 


ed to the end of the core. Such a core, complete, has two 
lead wires to commutator brought out through the center of the 
shaft. It is not easy to make and keep such separate pieces in 
line; of all things, a shaft should be continuous. 

Single coil armatures are not well adapted for motors, on 
account of their “dead center .” Even in dynamos the action is 
not easy, but rather jerky, and the current is pulsating. Greater 



FIGURE 170 . FIGURE I 7 1. 

uniformity can be attained by increasing the number of grooves 
for the wire, with a corresponding number of commutator seg¬ 
ments. In Figure 170 is a core with eight grooves. Such an 
armature for continuous running should be built up of sheet 
iron, clamped tightly together by means of nuts screwed on the 
shaft. A core 3 inches in diameter and 6 inches long will give 
a full horse power. The grooves should be § inch wide and f 
inch deep. In determining the size of wire to be used on an 
armature, 500 circular mils should be allowed for every ampere, 
from 30 to 36 inches in length for every volt is necessary. 

Suppose it is desired to wind the armature just described 
for no volts. Allowing the working efficiency to be 75 per 






ARMATURE WINDING. 


323 

cent., the current at one-horse power will be about 9 amperes. 
As only one-half the current is found in any one wire, a suit¬ 
able size for 4£ amperes must be chosen. No. 17 is the nearest 
that can be found in the wire tables. After insulating the 
giooves thoroughly, there should be room for 10 turns per layer, 
and six layers. Each section is to be wound 3 layers deep for 
the first round, leaving out loops at the beginning of each coil 
for connection to one half of the commutator. For the second 
round, 3 layers on top ot the others will give loops for the last 
half of the commutator. This is a simple multiple winding, 
similar to that referred to in the following paragraph. 

Any sort of projection from an armature core, between the 
coils, is a source of heating. As the edges of the core and 
pole piece pass, eddy currents are produced. It has been com¬ 
mon to dispense with all projections, and wind the wire over 
the entire smooth surface of the cores. Figure 171 shows a 
coil in position on such core. Figure 172 gives a perspective 

of the same, showing also the fibre pegs that keep the winding 
in place. In Figure 173, the whole winding is complete with 
the binding wires on. 

Siemens drum armatures, such as have been described, are of 
comparatively small diameter and need to be revolved at light 
speed in order to give the necessary peripheral velocity. Gramme 
ring armatures have a larger external diameter, the center por¬ 
tion being cut away, as shown in Figure 174. Notches cut in 
the internal circumference allow the arms of the “spider” to 
catch hold and attach the core to the shaft. 

The winding is in and out around the ring. One coil can 
be seen in position in Figure 175. In order to get the wire 

closely into the space allotted for each coil, it is necessary to 



Continuation 


DYNAMO-ELECTRIC MACHINERY. 






n 

C>. 

W 

c 

»—< 




















































ARMATURE WINDING. 


325 

lay the wires in twice as many layers on the inside as on the 
outside. After insulating the core, it is well to mark on the 
insulation the space for each coil, then there will be no chance 


figure 173. 

to' come out uneven. A core 7 inches outside diameter, 4^ in¬ 
side and 4^ inches axial length is suitable for a two-horse pow¬ 
er machine. For 110 volts put on No. 14 wire, three (on the 
outside) layers deep. The number of sections into which the 




figure i 74. 

winding and commutator is divided, depends on the voltage of 
the dynamo or motor, 10 volts between adjacent segments insures 
good working, 15 volts and ovei occasions spaiking. F01 110 





326 


DYNAMO-ELECTRIC MACHINERY. 


volts the whole difference of potential between the brushes will 
be at points half way around the commutator. Allowing io volts 
per segment there will be 11 segments; however, it would be 
well to make the commutator with an even 24 segments on 
account of ease in dividing the coils equally between the arms 
of the spider. 

A drum armature may be completely wound without making 
a cut in the wire. With a ring armature, the necessity of pass¬ 



ing the wire in and out through a small space compels each 
coil to be wound up of wire cut to the right length. This 

length can be roughly determined by winding the right number 
of turns with a cord and using the cord as a measure. The 

beginning of each coil should be marked in one color, and the 

end with another. Then with all the coils wound in the same 

direction, the beginning of one coil is to be connected to the 
end of the preceding, and a lead wire from the junction run to 
a commutator segment, or the two wires themselves may be 
soldered to the same segment. The winding becomes a contin- 

















ARMATURE WINDING. 


32 7 


uous path with taps at equidistant points leading to the commu¬ 
tator* A drum armature must have its winding specially adapted 
to the number of poles of the field magnets. Usually the fields 
ha\e but two poles and the winding is as described. A four 
01 six pole winding is very awkward and very seldom used in 
small machines. A ring armature is capable of running in a 



FIGURE 176. 

field with any number of poles. Figure 176 shows a four-pole 
field. The whole potential of the dynamo is then generated in 
the coils 90° apart. The brushes opposite to each other are con¬ 
nected in multiple. By connecting opposite coils of the arma¬ 
ture together by means of a common lead to commutator seg¬ 
ments, only two sets of brushes are necessary, these to be 90° 
apart. 

There is this advantage in a multipolar field, that the wire 
is in action oftener and hence slower speeds are allowable than 
can be efficiently produced with bipolar fields. 











DYNAMO-ELECTRIC MACHINERY. 


3 28 


APPENDIX D. 

FIELD MAGNET WINDING. 

(FIELD FORMULAE.) 

The calculations for the strength of the field, and the nec¬ 
essary current to produce it, are based upon the assumption 
that the lines of magnetic force obey a similar law to that for 
electric current, viz. ; that they vary directly as the magnetizing 
force and inversely as the resistance of the circuit. Kapp has 
made this a subject of investigation and finds a formula which 
fits approximately to observed facts. This is given below: 

P 

Z ~i44o“-|—L+ 2 - L 
and 

_ o.S P 

Z ~ iltoo"+A+IF 

Where Z— the total number of lines of force, P the ex¬ 
citing power in ampere-turns, a b the cross section of the arm¬ 
ature (Gramme ring in this case), c the arc spanned by each 
pole piece, d the distance between the polar surface of the 
magnets and the external surface of the armature core, 1 the 
average length of the magnetic circuit inside the armature, L 
the length of the magnetic circuit in the field magnets, and A 
B the cross sectional area of their core. See Figure 177. 

As the lengths are all given in inches, the exciting power 
in ampere turns, and the result Z in the same units chosen in 




FIELD MAGNET WINDING. 


329 


the armature formula, viz. : 6000 times larger than the absolute 
unit, so that the results obtained by this formula may be read¬ 
ily applied to the armature calculations. 

The hist of the two formulae is for well annealed wrought 
iron, and a wiought iron armature core, the second is best for 



FIGURE 177. 

cast iron magnets. The formulae only apply where the degree 
of magnetization of the field core is not higher than ten lines 
per square inch, and they give pretty fair results. Higher de¬ 
grees of magnetization demand more current than the formulae 
call for, and when the saturation point is approached, the in¬ 
creased power necessary over that given in the formulae is from 
40 to 100 per cent. 

Different specimens of iron will sometimes vary in their 
magnetic qualities, to such an extent that a formula will often 
not serve a much better purpose than a foundation upon which 
to base a good guess. The formulae of Kapp however are 
about the best that have been brought out as yet, and are near 

















33° 


DYNAMO-ELECTRIC MACHINERY. 


enough to the truth to enable one to build a dynamo, and not 
come very far from the calculated output. By multiplying the 
Z by the denominator of the fraction in the second term we 



get the value of P or the ampere-turns which we must 
upon our magnets. The formulae where double magnets 
used, are 


Z 

2 


li bC 1 nh 1 A F 


ab 


2L 

AB 


for wrought iron and for cast iron 


use 

are 


Z 



o.S P 


S00 65+H+ 


3_L 

AB 


The double field magnet can be made lighter than the sin¬ 
gle one for the same power, but requires more copper. Where 
expense is an item to be considered it must give way to the 
single magnet, but where weight is the chief point, it is to be 
preferred. See Figure 178. 


















INDEX. 


33 1 


INDEX. 

/ 


Action between a conducting wire 
and a magnetic field, u, 12. 

Alternating Current Dynamo, Direc¬ 
tions for using, 214-216. 

How to build, 191, 216. 

Types of commercial, 251-267. 

Ammeter in dynamo circuit, 216. 

Amperes, How to wind a dynamo ‘or 
motor for six, 51-53, 321. 
four to ten, 135, 136. 
ten to thirteen, 166. 
fifteen, 186, 187, 190. 
twenty to thirty, 208, 209. 
eight, 99, 109. 
nine, 322, 323. 

Apparatus for driving a dynamo by 
hand, 112. 

Armature, Drum, 38-40, 323, 326, 327. 

Gramme ring, 9, 36-37, 323, 326, 327. 

Methods of winding, 14-18. 

Pacinotti, 9, 291. 

Safe calculation for winding, 40. 

Shaft, 45, 50, 70-74, 148, 149, 179, 
201-204. 

Siemens’ shuttle, 9, 14, 35, 320. 

How to balance, 41, 42. 

How to wind, 35-42, 47, 51, 52,82-89, 
108, 109, 129-133, 164-170, 187, 
190, 209-212, 320-327. 

Core, How to make, 50, 51, 70-73, 
104-106, 118-121, 148-150, 179, 
182, 201-204. 

Thomson-Houston, 218-221. 


Armature, Edison, 230-232. 

Lund ell, 271. 

Crocker & Wheeler, 236, 278. 

Brush alternating current, 252-255. 
Assembling dynamos and motors, 61, 
92, 93, no, hi, 140, 163, 185, 
214-216. 

Bad Commutator, How to remedy, 
3 ID - 

Barlow’s rotating wheel, 9, 

Bearings for dynamos and motors, 56, 

57, 74-76, 104, 121, 122, 124, 147, 
178, 179, 192 - 197 - 

Binding, Wire for armature, 41. 
Blower, Thomson-Houston, 221-223. 
Board Connection, 106, 161, 185, 186, 
212-214 

Brush alternating current armature, 
252-255. 

Brush Electric Co.’s Dynamo, 249-255. 
Brush holder, Westinghouse, 298, 299. 
Brush holder, How to make, 45, 58, 
59, 77-8o, 106, 126-130, 158-160, 
183, 184, 205-206, 239. 

Brushes for dynamos and motors. 45, 

58, 78-80, 106, 126-130, 158-161, 
183, 184, 205, 206. 

Carbon Brush Holder, 79,127, 128. 
Calculations, Signification of signs 
used in. 317. 

Safe for winding an armature, 40. 




33 2 


DYNAMO-ELECTRIC MACHINERY. 



Commutator, How to make, 53-55, 
76-78, 106, 124-126, 152-158, 181, 
182. 

Thomson-Houston, 217, 218. 

Bad, 310. 

Sparking at, 310. 

Good lubricant for, 142. 

Collector for Faraday’s first machine, 

7 . 

How to make a, 204, 205. 

Connection board, 106, 161, 185, 186, 
212-214. 

Connections, for dynamos or motors, 
60, 92, 93, no, hi, 137-140, 
161-163, 185, 212-214. 

Conducting wire, action between, and 
magnetic field, n, 12, 

Controller, Thomson-Houston wall, 

o '> T ? n o 

Commercial Electric Co.’s dynamo or 
motor. 242-244. 

Compound wound dynamo, 25, 26. 

Core, armature, 50, 51, 70-73, 104, 106, 
118-121, 148-150, 179-182, 201- 
204. 

Crocker & Wheeler armature, 236, 
278. 

dynamo, 235-237. 

motor, 276-2S0. 

Currents, magneto, induction of, 7. 

Definitions of electrical and mag¬ 
netic units, 318, 319. 

Drum armature, 38-40, 323-327. 

Dynamo, alternating current, direc¬ 
tions for using, 214-216. 

Definition of, 11 

Compound wound, 25, 26. 

Magneto, 22, 23. 

Separately excited, 23, 24. 

Series wound, 24, 25. 


Dynamo, Shunt wound, 25. 

Hints on designing the, 32, 33. 
Directions for building a small, 49- 
64. 

one-fourth-horse-power, 65-96. 
two-light, 97-112. 
one-half-horse-power, 113-142. 
one-horse-power, 143-176. 
twenty-light, 177-190. 
an alternating current, 191-216. 
First continuous current, 8. 

First self-exciting, 8. 
Thomson-Houston arc, 217-223. 
300-horse power, 226-230. 
alternating current, 255-260, 262. 
Sperry, 223-226. 

Mather Railway, 226, 227. 

Short Railway, 233, 234. 

Crocker & Wheeler, multipolar, 235- 
237. 

C & C. Standard, 237-240. 

Edison, 2co-kilo-watt, 240-242. 
direct current, 230-233. 

General Electric Co.’s, 242-244. 
Wood electro-plating, 245, 246. 

Eddy “ 246-48. 

Brush, arc, 249, 250. 

alternating current, 251-255. 
Westinghouse, alternating current, 
261-264, 266, 267. 

Proper location for, 308. 

Starting the, 308, 309. 

Fails to generate, 309, 310. 

Hints for running, 310, 311. 
Ammeter in circuit of, 216. 

Hand apparatus for driving, 112, 
Dynamos, assembling, 61, 92, 93, no ( 
hi, 140, 163, 185, 214-216. 
Commercial, direct current, 217-250. 
alternating current, 251-267. 
electro-plating, 244-248. 



INDEX. 


333 


Dynamos, Pulley for, 59, 106, 11S-121, 
150, 182, 201-204. 

Pole pieces for, 55, 65, 66, 109, 116- 
118, 146-148, 177-179, 197-201. 

Eddy dynamo, for electro-plating, 
246-248. 

automatic electric motor, 274, 275. 

Edison dynamo, 230-233, 240-242. 

armature, 230-232. 

Electrical units, table of, 316. 

Electro-motor, first in the United 
States, 10. 

Electro-motive force, how to calculate 
for dynamos or motors, 14. 

Electro-magnets, residual magnetism 
in, 20, 21. 

Electro-plating dynamos, 244-248. 

Excelsior motor, 285, 286. 

Faraday’s discovery of magneto¬ 
electro induction of currents, 7. 

First dynamo machine, 7. 

Experiments, 7. 

Field formulae, 328-330. 

magnet, definition of, 20. 

magnet and frame, 19, 27-34, 43-45, 
54, 55, 65-70, 99-104, 116-11S, 

146-148, 177-U9, 197-201, 218, 
233, 235, 237, 242, 245, 246, 250, 
255, 262, 266, 272, 274, 276, 281- 
284, 288, 290, 293-297, 301, 329, 
330 - 

magnet, function of, 11, 12. 

Winding, method of, 19, 20, 328-330. 

Spools, 87, 89, 90, 133 - 135 , 1 7 1 — 1 73 ’ 
186, 190, 206-208, 257, 297. 

Magnetic, 13, 14. 

Magnetism, methods of exciting, 
22-26. 

First continuous current dynamo, 8. 


First self-exciting dynamo, 8. 

Electro-motor in the United States, 
10. 

Fuse wire, size of, to use for motor or 
dynamo, 96. 

Gauges, wire, table of, 312-315. 

Gramme ring armature, 9, 36, 37, 323, 
3 2 6, 327. 

Historical Notes, 7-10. 

Hints for running dynamos and 
motors, 310, 311. 

Induction, magneto, of currents, 7. 

Iron filings, Experiments of dusting 
in the magnetic field, 13, 14. 

Soft, best to use for dynamos, 33. 

Jenney, automatic motor, 272-274. 

Location, proper for dynamo, 308. 

Lubricant for commutator, 142. 

Lundell armature, 271. 

Motor, 268-272. 

Machine, Magneto, 22, 23. 

Magneto Induction of currents, 7. 

Magnetic units, table of, 318, 319. 

Field, action between a conducting 
wire and the, 11, 12. 

Mather dynamo, 226, 227 

Magnets, forms of field, 27-34, 329, 
33 °- 

For alternating currents, forms of 
field, 30. 

For direct currents, forms of field, 
27-30. 

field, how to wind, 90, 91, 99, 135, 
136, 170, 171, 190, 208-209. 

Magnetism, residual, 20, 21. 

Field, methods of exciting, 22-26. 




334 


DYNAMO-ELECTRIC MACHINERY. 


Management of dynamos and motors, 
30S-31 1 . 

Motor, C. & C. Standard, 237-240. 
General Electric Co.’s, 242-244. 
General Electric Co.'s, 150 K. W., 
237-240, 276-280. 

Eddy, 274,-275. 

Lundell, 268-272. 

Jenney automatic, 272-274. 
Excelsior, 285, 286. 

Ferret, 281-285. 

Tesla polyphase, 285, 287, 288. 
Directions for building a toy, 43-48. 
small, 49-64. 

one-fourth horse power, 65-96. 
one-half horse power, 113-142. 
one horse-power, 143-176. 
an alternating current, 191-216. 
Thomson-Houston, 280, 281, 289,291. 

Railway, 289-291. 

New G. E. railway, 291-293. 

Short gearless, 299-307. 
Westinghouse, railway, 293-299. 
Motors, Assembling, 61, 92, 93, no, 
hi, 140, 163, 185, 214, 216. 

Hints for running, 310, 311. 

Railway, types of, 289-307. 

Starting, directions for, 309. 
Stationary, 237-240,242-244,268-288. 
Pole pieces for, 55, 65, 66, 109, 116— 
118, 146-148, 177-179, 197-201. 

North and South pole of a dynamo, 
20. 

New G. E. railway motor, 291-293. 

Oiling Rings, 121, 122. 

Oil cups, 104. 

Oil on commutator, 311. 

\ 

Pacinotti ring armature, 9, 291. 
Perret motor, 281-285. 


Pole, magnetic, north or south, 20. 

Pieces, for dynamos or motors, 55, 
65, 66, 109, 116-118, 146-148, 

i 77 -i 79 ^ I 97 ~ 201 - 

Potential, how to obtain constant, 31. 

Polyphase system, Tesla’s, 263-266. 

Principles of dynamo machines, n- 
21. 

Pulley for dynamos or motors, 59,106, 
118-121, 150, 182, 201-204. 

Railway motors, types of, 289-307. 

Thomson-Houston water-p roof, 

289-291. 

New General Electric, 291-293. 

Westinghouse, 293-299. 

Short gearless, 299-307. 

Residual magnetism, 20, 21. 

Rule-of-thumb for finding direction of 
current, 15. 

Safety fuse, size of, to use for a 
motor or dynamo, 96. 

Separately-excited dynamo, 23, 24. 

Series-wound dynamo, 24, 25. 

Shaft, armature, for dynamos and 
motors, 45, 50, 70-74, 148, i49> 
179, 201-204. 

Short railway dynamo, 233, 234. 

Shunt-wound dynamo, 25. 

Shuttle armature, Siemen’s, 9, 14, 35, 
320. 

Sperry dynamos, 223-226. 

Spools, field, 87, 89, 90, 133—135, 171— 
173, 186-190, 206-208, 257, 297. 

Starting the dynamo, 308, 309. 

System, Tesla polyphase, 263-266. 

Table showing difference between 
wire gauges, 312, 

Of different gauges, with their 
diameters and area in mils, 313. 






INDEX. 


335 


Table of dimensions and resistances 
of pure copper wire, 314, 315. 

Of electrical units, 316. 

Of significations of signs used in 
calculations, 317. 

Table of definitions of electrical and 
magnetic units, 318, 316. 

Tables, useful, 312-319. 

Tesla polyphase motor, 285, 2S7, 2S8. 
system, 263-266. 

Thomson-Houston armature, 218-221. 
dynamos, 217-223, 226-230, 255-260, 
262. 

wall controller, 221, 222. 
motors, 280, 281, 289-291. 
Commutator, 217, 218. 

Toy motor, how to build a, 43-48. 
Transformer, 260. 

United States, first dynamo made 
in the, 10. 

Useful tables, 312-319. 

Using an alternating current dynamo, 
directions for, 214-216. 

Volts, How to wind a field magnet 
for seven, 91. 
twenty-five, 91, 99, 208. 
fifty, 90, 91, 136, 208. 
fifty-two, 170, 171. 
eighty, 190. 

one hundred and ten, 91, t 35, 136, 
208. 

an armature for seven, 88. 
twenty-five, 88, 89, 99. 
thirty-five, 321. 

fifty, 84-87, 131, 133, 209, 210. 
fifty-two, 166. 
eighty, 186, 187. 

one hundred and ten, 89, 131—133, 
322, 323, 325. 

two hundred and twenty, 176. 


Wall controller, Thomson-Houston, 
~~ 1 ? d -- 

Westinghouse dynamos and motors, 
261-264, 266, 267, 293-299. 

Wheel, Barlow’s rotating, 9. 

Wind armatures, how to, 35-42, 47, 
5C 5 2 > 82-89, 108, 109, 129-133, 
164—170, 187, 190, 209—212, 320- 

3 2 7 - 

Winding armatures, methods of, 14- 
18. 

Field magnets, methods of, 22-26. 

Safe calculation for a drum arma¬ 
ture, 40. 

Dynamos or motors for four to ten 
amperes, 135, 136. 
six amperes, 51-53, 321. 
eight amperes, 99, 109. 
nine amperes, 322, 323. 
ten to thirteen amperes, 166. 
fifteen amperes, 186, 187, 190. 
twenty to thirty amperes, 208, 209. 
seven volts, 88, 91. 
twenty-five volts, 88, 89, 99, 208. 
fifty volts, 84-S7, 90, 91, 133-136, 
208-210. 

fifty-two volts, 170, 171, 186, 187. 
thirty-five volts, 321. 
eighty volts, 186, 187, 190. 
one hundred and ten volts, 89, 91, 
1 3 1 —1 33 » i 3 S» 2 °8, 3 22 > 3 2 3 > 

325 - 

two hundred and twenty volts, 
176. 

Wire binding for armature, 41. 

Wood dynamo for electro-plating, 
244-246. 

Yoke, for dynamos or motors, how to 
build, 54, 55, 78-82,106,126-129, 
158, 183, 184. 






CASTINGS AND PARTS 


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FOR THE 


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1-4 Horse Power 
1-8 Horse Power 

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AND THE 


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Described in this Book 
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*»“AN IMPORTANT WORK-®* 


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“Experimental * Electricity,” 

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AUTHOR OF “EVERYBODY’S HAND-BOOK OF ELECTRICITY,” 
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This book contains about 200 pages, and is fully illus¬ 
trated with about 50 engravings. 

It will give practical information upon the following 
subjects : 

Chap. 1 .—Some Easy Experiments in Electricity and 
Magnetism. 

* 2 .—How to Make Electric Batteries. 

“ 3.— How to Make a Galvanometer. 

“ 4 . — How to Make an Electric Bell. 

“ 5 . —How to Make an Induction Coil. 

“ 6.—How to Make a Magneto Machine. 

“ 7 .—How to Make a Telegraph Instrument. 

“ 8.—How to Make an Electric Motor. 

“ 9 .—How to Make a Dynamo. 

“ 10.—Electric Gas Lighting and Bell Fitting. 

Some practical directions for amateurs. 

“ 11.—Some information in regard to Electric Lamps. 

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BY EDWARD TREVERT. 

ILLUSTRATED with nearly 50 Engravings and contains a 
vast amount of valuable information, both in theory and 
practice upon this subject. It also contains working 
directions for Winding Dynamos and Motors, with addi¬ 
tional Descriptions of some of the apparatus made by the 
several leading Electiical Companies in the U. S. 


-CONTENTS.- 

Introduction. 

Chapter 1 . —The Armature in Theory. 
Chapter 2. —Forms of Armatures. 
Chapter 3.—Drum Winding. 

Chapter 4.—Field Winding. 

Chapter 5.—Field Formulae. 

Chapter 6. —General Methods of Winding. 
Chapter 7.—Field Winding—concluded. 
Chapter 8. —Dynamos. 

Chapter 9.—Motors. 


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*»“AN IMPORTANT WORK-®* 


A BOOK FOR EVERYBODY. 

NOW READY. 

“Experimental ® Electricity,” 

BY EDWARD TREVERT. 

AUTHOR OF “EVERYBODY’S HAND-BOOK OF ELECTRICITY,” 
AND “HOW TO MAKE ELECTRIC BATTERIES AT HOME.” 


This book contains about 200 pages, and is fully illus¬ 
trated with about 50 engravings. 

It will give practical information upon the following 
subjects : 

Chap. 1.— Some Easy Experiments in Electricity and 
Magnetism. 

y.—H ow to Make Electric Batteries. 

“ 3.— How to Make a Galvanometer. 

“ 4. — How to Make an Electric Bell. 

“ 5.—How to Make an Induction Coil. 

“ 6.—How to Make a Magneto Machine. 

“ 7.—How to Make a Telegraph Instrument. 

“ 8.—How to Make an Electric Motor. 

“ 9.—How to Make a Dynamo. 

“ 10.—Electric Gas Lighting and Bell Fitting. 

Some practical directions for amateurs. 

“ ip—Some information in regard to Electric Lamps. 

JUST THE BOOK FOR AMATEURS. 

Price, Clotli Bound, $1.00. Postage Paid. 

Send in your orders at once and they will be 
promptly filled. 


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-FOR- 

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-AND 



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ILLUSTRATED with nearly 50 Engravings and contains a 
vast amount of valuable information, both in theory and 
practice upon this subject. It also contains working 
directions for Winding Dynamos and Motors, with addi¬ 
tional Descriptions of some of the apparatus made by the 
several leading Electiicai Companies in the U. S. 


-CONTENTS.- 

Introduction. 

Chapter 1 . —The Armature in Theory. 
Chapter 2.— Forms of Armatures. 
Chapter 3.—Drum Winding. 

Chapter 4.—Field Winding. 

Chapter 5. —Field Formulae. 

Chapter 6 . — General Methods of Winding. 
Chapter 7.—Field Winding—concluded. 
Chapter 8. —Dynamos. 

Chapter 9.—Motors. 


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How to Make Electric Batteries at Home. 
Experimental Electricity. 

Dynamos and Electric Motors. 


“Electricity and its Recent Applications," 


Containing nearly 350 pages and about 250 Illus. 

This work is printed on extra fine heavy paper, is bound in * 
neat cloth binding, and lettered in gold. It is particu¬ 
larly adapted to the use of Students. 

-CONTENTS,- 

Chap. 1.—Electricity and Magnetism. 

Chap. 2.—Voltaic Batteries. 

Chap. 3.—Dynamos, and How to Build One. 

Chap. 4.— The Electric Arc, and The Arc Lamp. 

Chap. 5.—Electric Motors and How to Build One. 

Chap. 6.—Field Magnets. 

Chap. 7. —Armatures. 

Chap. 8.—The Telegraph and Telephone. 

Chap. 9.—Electric Bells.—How Made, Flow Used. 

Chap. 10.—How to Make an Induction Coil. 

Chap. 11.—The Incandescent Lamp. 

Chap. 12.—Electrical Mining Apparatus. 

Chap. 13.—The Modern Electric Railway. 

Chap. 14.—Electric Welding. 

Chap. 15.— Some Miscellaneous Electric Inventions of the 
Present Day. 

Chap. 16.—Electro-Plating. 

Chap. 17.— Electric Gas Lighting Apparatus. 

Chap. 18.—Electrical Measurement. 

Chap. 19.—Resistance and Weight Table for Cotton and Silk 
Covered and Bare Copper Wire. 

Chap. 20.—Illustrated Dictionary of Electrical Terms and 
Phrases. 


PRICE $2.00. 


BUBIFR PUBLISHING CO., Lynn, 


Mass 








Latest and Best Electrical Books 

For Students and Amateurs* 


TREVERT’S WORKS. 

Experimental Electricity.... • $i.oo 

Everybody’s Hand Book of Electricity .. - 5 ° 

How to make Electric Batteries at Home.. > 2 5 

Dynamos and Electric Motors and all about them ....... .50 

Armature and Field Magnet Winding . . . 1.5° 

How to Make a Dynamo. .. .10 

Electric Railway Engineering. 2*00 

Electricity and its Recent Applications. 2.00 

A Practical Treatise on Electro Plating. .50 

How to Make and Use Induction Coils .. 0 .50 

Practical Directions for Electric Gas Lighting and Bell Fitting lor 

Amateurs. . - 5 ° 

Electrical Measurements for Amateurs . 1.00 

How to Build Dynamo Electric Machinery.. 2.50 

Electricity for Students.... 1.00 

How to Make an Electric Motor... -to 

MISCELLANEOUS AUTHORS. 

Questions and Answers about Electricity. - 5 ° 

Edited by E. T. Bubier, 2d. 

A Practical Treatise on the Incandescent Lamp.. .50 

J. E. Randall. 

Electric Motor Construction, for Amateurs.. 1.00 

C. D. Parkhurst. 

A Practical Hand-Book of Modern Photography, for Amateurs . . .50 

E. T. Bubier, 2d. 

Arithmetic of Magnetism and Electricity . . .. 1.00 

John T. Morrow and Thorburn Reid. 

How to Make and Use a Telephone. Geo. 11. Cary. 1.00 

Transformers; Their Theory, Construction and Application Simplified 1.25 
Caryl D. Haskins. 

What is Electricity? Elihu Thomson. .25 

How to make a 1 horse power Motor or Dynamo. A. E. Watson . . .50 

A Hand Book of Wiring Tables. A. E. Watson. . .75 

How to Build an Alternating Current Dynamo or Motor. Cloth . . .50 

A. E. Watson. 

How to Build a 1-4 horse-power Motor or Dynamo. Cloth ..... .50 

A. E. Watson. 

How to Build a 1 2 horse power Motor or Dynamo. Cloth ..... .50 

A. E. Watson. 

How to Build a 50-Light Dynamo. A. E. Watson ........ .50 

The Electric Railway. Fred. H. Whipple.• . . . . 1.00 

The Electric Railway 01 To-Day. H. B. Prindle. .50 

A Treatise on Electro Magnetism. D. E. Connor, C. E. .50 

A Popular Lecture on Light. Prof. Elihu Thomson.. .20 

How to Make and Use the Storage Battery. P. B. Warwick ..... 1.50 

How to Make and Run a Gas Engine.. .75 

Electricians’ Handy Book A. E. Watson. Cloth $2.50. Leather . 3.00 


Bubiet Publishing Co., 

P. O. Box 709, LYNN, MASS. 

Send Money by P. O. Order or Registered Letter at our risk. 
















































A 


NEW BOOK! 


BY EDWARD TREVERT. 


AUTHOR OF 


Everybody’s Hand-Book of Electricity. 
How to Make Electric Batteries at Home. 
Experimental Electricity. 

Dynamos and Electric Motors. 


“Electricity and its Recent Applications.” 


Containing nearly 350 pages and about 250 Illus. 

This work is printed on extra fine heavy paper, is bound in * 
neat cloth binding, and lettered in gold. It is particu¬ 
larly adapted to the use of Students. 

-CONTENTS.- 

Chap. 1.—Electricity and Magnetism. 

Chap. 2. —Voltaic Batteries. 

Chap. 3.—Dynamos, and How to Build One. 

Chap. 4.— The Electric Arc, and The Arc Lamp. 

Chap. 5. —Electric Motors and How to Build One. 

Chap. 6.—Field Magnets. 

Chap. 7.— Armatures. 

Chap. 8.—The Telegraph and Telephone. 

Chap. 9.—Electric Bells.—How Made, How Used. 

Chap. 10.—How to Make an Induction Coil. 

Chap. 11.—The Incandescent Lamp. 

Chap. 12.—Electrical Mining Apparatus. 

Chap. 13.—The Modern Electric Railway. 

Chap. 14.—Electric Welding. 

Chap. 15.—Some Miscellaneous Electric Inventions of the 
Present Day. 

Chap. 16.—Electro-Plating. 

Chap. 17.—Electric Gas Lighting Apparatus. 

Chap. 18.—Electrical Measurement 

Chap. 19.—Resistance and Weight Table for Cotton and Silk 
Covered and Bare Copper Wire.. 

Chap. 20.—Illustrated Dictionary of Electrical Terms and 
Phrases. 


PRICE $2.00. 


BUB/FR PUBLISHING CO., Lynn, Mass 









Latest and Best Electrical Books 

For Students and Amateurs* 


TREVERT’S WORKS. 

Experimental Electricity.. • $1.00 

Everybody’s Hand Book of Electricity .. - 5 ° 

How to make Electric Batteries at Home.. * 2 5 

Dynamos and Electric Motors and all about them . . . . . . . . > 5 ° 

Armature and Field Magnet Winding . . .. 1.50 

How to Make a Dynamo.. .. .10 

Electric Railway Engineering.. 2.00 

Electricity and its Recent Applications. 2.00 

A Practical Treatise on Electro Plating. .50 

How to Make and Use Induction Coils . ... . . “ .50 

Practical Directions for Electric Gas Lighting and Bell Fitting lor 

Amateurs.. • . -S° 

Electrical Measurements for Amateurs . . .. 1.00 

How to Build Dynamo Electric Machinery.. 2.50 

Electricity for Students.. . . 1.00 

How to Make an Electric Motor. -io 

MISCEEEANEOUS AUTHORS. 

Questions and Answers about Electricity. . .50 

Edited by E. T. Bubier, 2d. 

A Practical Treatise on the Incandescent Lamp.. .50 

J. E. Randall. 

Electric Motor Construction, for Amateurs. . 1.00 

C. D. Parkhurst. 

A Practical Hand-Book of Modern Photography, for Amateurs . . .50 

E. T. Bubier, 2d. 

Arithmetic of Magnetism and Electricity. 1.00 

John T. Morrow and Thorburn Reid. 

How to Make and Use a Telephone. Geo. 11. Cary. 1.00 

Transformers; Their Theory, Construction and Application Simplified 1.25 
Caryl D. Haskins. 

What is Electricity? Elihu Thomson. .25 

How to make a 1 horse power Motor or Dynamo. A. E. Watson . . . .50 

A Hand Book of Wiring Tables. A. E. Watson. .75 

How to Build an Alternating Current Dynamo or Motor. Cloth . . .50 

A. E. Watson. 

H ow to Build a 1-4 horse-power Motor or Dynamo. Cloth. 50 

A. E. Watson. 

How to Build a 1 2 horse-power Motor or Dynamo. Cloth ..... .50 

A. E. Watson. 

How to Build a 50-I.ight Dynamo. A. E. Watson. .50 

The Electric Railway. Fred. H. Whipple. ’ ... . 1.00 

The Electric Railway 01 To-Day. H. B. Prindle. .50 

A Treatise on Electro Magnetism. D. E. Connor, C. E. .50 

A Popular Lecture on Light. Prof. Elihu Thomson. .20 

How to Make and Use the Storage Battery. P. B. Warwick .... 1.50 

How to Make and Run a Gas Engine. .75 

Electricians’ Handy Book. A. E. Watson. Cloth $2.50. Leather . 3.00 


Bubiei' Publishing Co., 

P. O. Box 709, LYNN, MASS. 

Send Money by P. O. Order or Registered Letter at our risk. 













































° n >y 1 O Cents. Only \ Q Cents 

PRACTICAL BOOKS. 

-ON- 


electricity. 


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Lv 

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16. 

No. 



How to make a Dynamo. 

How to make a Telephone. 

How to make an Electric Motor. 

How to make a Storage Battery. 

How to make a Wimshurst Electric 
Machine. 

How to make a Magneto Machine. 

How to make a Medical Induction Coil. 
How to make a Pocket Accumulator. 
How to make a Plunge Battery. 

How to make a Voltmeter. 

How to make a Galvanometer. 

How to make a Hand Dynamo. 

How to make a Talking Machine. 

How to make a 1-8 H.P. Dynamo or 
Motor. 

How to make a Toy Motor. 

How to make an Electric Bell. 

How to make a Telegraph Instrument. 


These Books are illustrated and the price is only 


10 CENTS EACH. 

Babiep Publishing Co., 


Lynn, Mass. 


P. O. Box 709 . 









BUBIER’S 

Popular Eleetrieian. 


A SCIENTIFIC ILLUSTRATED MONTHLY 

For the Amateur and Public at Large. 

Containing descriptions of all the new inventions as fast as 
they are patented; also lists of patents filed each month at the 
Patent Office in Washington, D. C. Interesting articles by 
popular writers upon scientific subjects written in a way that 
the merest beginner in science can understand. Also a Que$ 
tion and Answer Column rree to all subscribers. 

Price, Postpaid, 50c. a Year. 

SAMPLE COPY FIVE CENTS. 

Send for it. You will be more than pleased. 

Bubier Publishing Co., Lynn, Mass. 









° nl y 1 O Cents. Only \ Q Cents 

PRACTICAL BOOKS. 


-ON 


ELECTRICITY. 


No. 

1. 

No. 

2. 

No. 

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No. 

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: 5 - 

No. 

16. 

No. 



How to make a Dynamo. 

How to make a Telephone. 

How to make an Electric Motor. 

How to make a Storage Battery. 

How to make a Wimshurst Electric 
Machine. 

How to make a Magneto Machine. 

How to make a Medical Induction Coil. 
How to make a Pocket Accumulator. 
How to make a Plunge Battery. 

How to make a Voltmeter. 

How to make a Galvanometer. 

How to make a Hand Dynamo. 

How to make.a Talking Machine. 

How to make a 1-8 H.P. Dynamo or 
Motor. 

How to make a Toy Motor. 

How to make an Electric Bell. 

How to make a Telegraph Instrument. 


These Books are illustrated and the price is only 


10 CENTS EACH. 

Babiep Publishing Co., 

Lynn, Mass. 


P. O. Box 709. 












BUBIER’S 

Popular Electrician. 


A SCIENTIFIC ILLUSTRATED MONTHLY 

For the Amateur and Public at Large. 

Containing descriptions of all the new inventions as fast a3 
they are patented; also lists of patents filed each month at the 
Patent Office in Washington, D. C. Interesting articles by 
popular writers upon scientific subjects written in a way that 
the merest beginner in science cnn understand. Also aQues 
tion and Answer Column rree to all subscribers. 

Price, Postpaid, 50c. a Year. 

SAMPLE COPY FIVE CENTS. 

Send for it. You will be more than pleased. 

Bubier Publishing Co., Lynn, Mass. 


18 2 92 































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